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PostPosted:Fri May 13, 2022 5:06 pm 
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I don’t trust the wheel specifications that are published on various Internet websites, but it might be worth investigating 2000~2004 Lotus Exige S1 wheels, which are said to have a 95•25 mm (i.e. 3¾ inch) PCD and 38 mm wheel-offset, with a 56•6 mm centre-bore; which I discovered a few years ago, when researching possible substitute wheels for my 1974 Triumph Toledo 1300 “HL Special”.

http://www.wheel-fitment.com/PCD.html

http://www.wheel-fitment.com/PCD/4x95.25.html

http://www.wheel-fitment.com/PCD/4x95.25/56.6.html

http://www.wheel-fitment.com/car/Lotus/

http://www.wheel-fitment.com/car/Lotus/ ... 2004).html

Lotus Exige S1 (2000~2004)
PCD : 95.25 mm
Centre bore 56.6 mm
Offset: 38 mm

https://tireswheels.org/lotus/

https://tireswheels.org/lotus-exige-s1-2000-2004/

Further investigation indicates that one of the 2004 Lotus Exige models is fitted with 195/55 R16 tyres on 16 inch wheels, which is probably NOT what you would be prepared to consider.

https://www.pirelli.com/tyres/en-gb/car ... exige/2004

Various Lotus Exige S1 wheels

Image

Image

_________________
Regards.

Nigel A. Skeet

Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.

https://www.linkedin.com/profile/view?id=308177758

Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)

Onetime member + magazine editor & technical editor of Volkswagen Type 2 Owners' Club


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PostPosted:Fri May 13, 2022 11:35 pm 
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TDC Shropshire Area Organiser

Joined:Sun Aug 21, 2011 4:12 pm
Posts:6581
Location:Highley, Shropshire
Quote:
I don’t trust the wheel specifications that are published on various Internet websites, but it might be worth investigating 2000~2004 Lotus Exige S1 wheels, which are said to have a 95•25 mm (i.e. 3¾ inch) PCD and 38 mm wheel-offset, with a 56•6 mm centre-bore; which I discovered a few years ago, when researching possible substitute wheels for my 1974 Triumph Toledo 1300 “HL Special”.

http://www.wheel-fitment.com/PCD.html

http://www.wheel-fitment.com/PCD/4x95.25.html

http://www.wheel-fitment.com/PCD/4x95.25/56.6.html

http://www.wheel-fitment.com/car/Lotus/

http://www.wheel-fitment.com/car/Lotus/ ... 2004).html

Lotus Exige S1 (2000~2004)
PCD : 95.25 mm
Centre bore 56.6 mm
Offset: 38 mm

https://tireswheels.org/lotus/

https://tireswheels.org/lotus-exige-s1-2000-2004/

Further investigation indicates that one of the 2004 Lotus Exige models is fitted with 195/55 R16 tyres on 16 inch wheels, which is probably NOT what you would be prepared to consider.

https://www.pirelli.com/tyres/en-gb/car ... exige/2004

Various Lotus Exige S1 wheels

Image

Image
And the "Team Dynamics" Wheel in the lower of your 2 pics is just discernible as a 17" which is even less suitable. But it does mean that Team Dynamics (a mainly aftermarket supplier and a fairly budget one at that) have blanks that will cover our requisite PCD and offset, might be worth an email to see if they can supply it in smaller diameters! With maybe a small choice of styles!

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.


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PostPosted:Sat May 14, 2022 5:06 pm 
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Joined:Tue May 06, 2014 3:38 pm
Posts:427
Location:South Benfleet, Essex
Quote:
I don’t trust the wheel specifications that are published on various Internet websites, but it might be worth investigating 2000~2004 Lotus Exige S1 wheels, which are said to have a 95•25 mm (i.e. 3¾ inch) PCD and 38 mm wheel-offset, with a 56•6 mm centre-bore; which I discovered a few years ago, when researching possible substitute wheels for my 1974 Triumph Toledo 1300 “HL Special”.

http://www.wheel-fitment.com/PCD.html

http://www.wheel-fitment.com/PCD/4x95.25.html

http://www.wheel-fitment.com/PCD/4x95.25/56.6.html

http://www.wheel-fitment.com/car/Lotus/

http://www.wheel-fitment.com/car/Lotus/ ... 2004).html

Lotus Exige S1 (2000~2004)
PCD : 95.25 mm
Centre bore 56.6 mm
Offset: 38 mm

https://tireswheels.org/lotus/

https://tireswheels.org/lotus-exige-s1-2000-2004/

Further investigation indicates that one of the 2004 Lotus Exige models is fitted with 195/55 R16 tyres on 16 inch wheels, which is probably NOT what you would be prepared to consider.

https://www.pirelli.com/tyres/en-gb/car ... exige/2004

Various Lotus Exige S1 wheels

Image

Image
Quote:
And the "Team Dynamics" Wheel in the lower of your 2 pics is just discernible as a 17" which is even less suitable. But it does mean that Team Dynamics (a mainly aftermarket supplier and a fairly budget one at that) have blanks that will cover our requisite PCD and offset, might be worth an email to see if they can supply it in smaller diameters! With maybe a small choice of styles!

Steve

It's always worth asking Steve! :) You never know; you might get lucky!?! :wink:

It wasn't clear from the picture reference, which Lotus Exige model was fitted with those "Team Dynamics" 17 inch wheels in the bottom picture. Keep in mind that NOT all of the Lotus Exige models use wheels of 95•25 mm (i.e. 3¾ inch) PCD.

If I had to choose between the two wheels, I would prefer the top one, which is 16 inches diameter. Given the mention of the 196/55 R16 tyres for one model, the wheels might possibly less than 7 inches wide, unlike the 16 inch wheels of the MGTF.

_________________
Regards.

Nigel A. Skeet

Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.

https://www.linkedin.com/profile/view?id=308177758

Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)

Onetime member + magazine editor & technical editor of Volkswagen Type 2 Owners' Club


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PostPosted:Sat May 14, 2022 10:32 pm 
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PostPosted:Sun May 15, 2022 8:52 am 
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I've had numerous sets of different wheels in differing sizes on my Dolomites. 185/55x15s on anything are awful, far too heavy making every response of the car lumpen. I can only imagine 195/55x16 being even worse, don't do it, Nigel!

On 13s I like 175/65 or 185/60, on 14s 185/50 seem best, but Michelins in 175/55 work well too, on 15s I've got away with 195/45s but much prefer 185/45s.

Obviously innumerable differences in terms or brake size, offset, vehicle height etc, but if you want to retain any feel and lightness of touch, those are what I'd recommend.

PS Yes, Team Dynamics are well able to produce wheels in 95.25 PCD, but none are very attractive and they're much heavier than you'd think.


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PostPosted:Sun May 15, 2022 3:30 pm 
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Joined:Sun Aug 21, 2011 4:12 pm
Posts:6581
Location:Highley, Shropshire
Quote:
I've had numerous sets of different wheels in differing sizes on my Dolomites. 185/55x15s on anything are awful, far too heavy making every response of the car lumpen. I can only imagine 195/55x16 being even worse, don't do it, Nigel!

On 13s I like 175/65 or 185/60, on 14s 185/50 seem best, but Michelins in 175/55 work well too, on 15s I've got away with 195/45s but much prefer 185/45s.

Obviously innumerable differences in terms or brake size, offset, vehicle height etc, but if you want to retain any feel and lightness of touch, those are what I'd recommend.

PS Yes, Team Dynamics are well able to produce wheels in 95.25 PCD, but none are very attractive and they're much heavier than you'd think.
On the Carledo, I ran the 5 spoke 6x15 MGF rims (which you don't rate) with 195/50 Toyo Proxes and it was fine, better than fine really, proper point and squirt handling, utterly predictable and great fun. No bump steer, heaviness or lack of response. But the car had been thoroughly lightened and set up for track work and none of the suspension or steering had gone unaltered. I'd been worried about the car being more than a tad over-tyred having run into the same problem years ago on an old Nova I owned, I tried 6x15 Cav SRI rims with 195/60s and it was AWFUL! Bump steer, massive torque steer, they came off again within the day! None of these issues troubled the Carledo though and the wheel/tyre choice stayed constant for 11 years and 3 sets of tyres. If it ain't broke.......

The jury is still out on the Dolomega with 185/60s on its 14" JBW rims there is a nasty stiffness and heaviness to the steering which is still currently undiagnosed, but i'm pretty sure it isn't down to tyre/wheel choice, i've done something wrong somewhere, probably in the intermediate column area. It may even be a partial seizure in the UJs, they went on early in the buildup of the car and it was several years between fitting and first road test.

I've bought the set of MGF 6 spoke 6x15s to try on the Dolomega with probably 185/60/15s (if the 185/55s on the old MGF front wheels clear the rear arches) If it doesn't work, i'll just move them on again, they weren't expensive.

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.


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PostPosted:Thu May 19, 2022 7:19 pm 
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Whilst on the subject of Lotus cars which use wheels of 95•25 mm (i.e. 3¾ inch) PCD, let us not forget the Caterham 7 (i.e. a Lotus 7 by another name) and the later first-generation Lotus Elise, whose wheel-offsets are sadly inappropriate for the Triumph Toledo & Dolomite.

http://www.wheel-fitment.com/PCD.html

http://www.wheel-fitment.com/PCD/4x95.25.html

http://www.wheel-fitment.com/PCD/4x95.25/56.6.html

http://www.wheel-fitment.com/car/Lotus/

http://www.wheel-fitment.com/car/Lotus/ ... 2001).html

The 1992~1998 Caterham 7 Classic uses wheels of 95•25 mm (i.e. 3¾ inch) PCD & 15 mm wheel-offset

The 1996~2001 Lotus Elise S1 uses wheels of 95•25 mm (i.e. 3¾ inch) PCD & 10 mm wheel-offset

If there are wheel manufacturers such as "Team Dynamics" making alternative wheels for these cars, then as with 2000~2004 Lotus Exige S1, they might be able to make wheels of the same style as the Lotus 7 or Lotus Elise S1, but with a wheel-offset of circa 35 mm, appropriate to the Triumph Toledo & Dolomite.
Quote:
It's all about ET (or offset as its sometimes known) Now the Sprint's standard ET is a very high 35 for a car of that vintage and along with the 4x95.25 PCD, limits wheel choice considerably.
The Dolomite Sprint wheels’ 35 mm wheel-offset is not especially high for a vehicle of mid-1970s to early-1980s vintage!

The 1971~79 VW Type 2 Transporter T2 and 1980~92 VW Transporter T3, have factory-fitted 5½ x 14 inch steel wheels of 39 mm wheel-offset and many Mercedes cars of 1970s vintage and later decades have wheels of 37 mm wheel-offset; having a common 5 x 112 mm PCD and 66 mm centre-bore; which is why second-hand Mercedes wheels in various styles, of 14 inches, 15 inches & 16 inches diameter, are commonly substituted on Volkswagen vans like my 1973 VW “1600” Type 2 Westfalia Continental motor-caravan.

Forum Index > Bay Window Bus > Mercedes wheels on a Bus

https://www.thesamba.com/vw/forum/viewt ... p?t=353046

Forum Index > Bay Window Bus > Mercedes Wheels question

https://www.thesamba.com/vw/forum/viewt ... p?t=373743

2002/03 Mercedes C-Class 7 x 16 inch alloy wheels with 5 x 112 mm PCD & 37 mm wheel-offset for my 1973 VW Type 2

Image

I would have preferred Mercedes wheels with 35 mm wheel-offset, of the following style, but being of 8 x 16 inch size, they were too wide for my 1973 VW Type 2

Image

Some other cheap second-hand Mercedes 7 x 16 inch alloy wheels, with 37 mm wheel-offset, that I was considering, are as follows

Image

Image

This type of 5-slot wheel was advertised a few years ago on Gumtree. Strangely there were two people at the same time in Swansea, both advertising these wheels at £10 each: four wheels for a total of £40 and two wheels for a total of £20. I later regretted not buying them for such a modest sum, but at that time there were uncertainties about various compatible technical specifications, that I was still trying to resolve.

_________________
Regards.

Nigel A. Skeet

Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.

https://www.linkedin.com/profile/view?id=308177758

Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)

Onetime member + magazine editor & technical editor of Volkswagen Type 2 Owners' Club


Last edited by naskeet on Sat Jun 04, 2022 8:23 pm, edited 2 times in total.

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PostPosted:Sun May 22, 2022 3:55 pm 
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Quote:
I've had numerous sets of different wheels in differing sizes on my Dolomites. 185/55x15s on anything are awful, far too heavy making every response of the car lumpen. I can only imagine 195/55x16 being even worse, don't do it, Nigel!

On 13s I like 175/65 or 185/60, on 14s 185/50 seem best, but Michelins in 175/55 work well too, on 15s I've got away with 195/45s but much prefer 185/45s.

Obviously innumerable differences in terms or brake size, offset, vehicle height etc, but if you want to retain any feel and lightness of touch, those are what I'd recommend.

One of the concerns and/or interests that are commonly expressed about changing tyre sizes, are the variation in overall engine gearing and speedometer calibration.

It appears that your preferred choices of tyre size, are of circa 4•6% to 7•5% smaller external circumference, than the factory-standard 155 SR13 tyres; which is equivalent to a significant increase in final-drive ratio! Using some of your preferred tyre sizes on a Triumph Dolomite 1850, would be roughly equivalent to substituting a 3•89:1 final-drive ratio in place of the original 3•63:1 final-drive ratio, which might have been what you intended!?!

In a 14-page, A5-format magazine technical article [published in either the Automobile Association’s “DRIVE” magazine or Motor-Caravanners’ Club’s “Motor-Caravanner” magazine, but believed to be the former] dating from early-1992, I found a statement that for standard-profile tyres such as 155 SR13 (later re-designated 155 R13), the aspect ratio was 82%, which is consistent with the 82% & 83% that I found in various papers, that were published in a wheel & tyre industry engineering conference proceedings from the early-1980s.

175 R13 => 175/83 R13 – overall external circumference = 1949•9 mm
175 R13 => 175/82 R13 – overall external circumference = 1939•0 mm (5•62% larger than 155/82 R13) [Nigel’s tyres 1974/75~87]
175 R13 => 175/80 R13 – overall external circumference = 1917•0 mm

155 R13 => 155/83 R13 – overall external circumference = 1845•6 mm
155 R13 => 155/82 R13 – overall external circumference = 1835•9 mm
155 R13 => 155/80 R13 – overall external circumference = 1816•4 mm

185/70 R13 – overall external circumference = 1851•0 mm (0•82% larger than 155/82 R13) [Nigel’s tyres from 1987 onward]

175/70 R13 – overall external circumference = 1807•0 mm (1•57% smaller than 155/82 R13)

175/65 R13 – overall external circumference = 1752•0 mm (4•57% smaller than 155/82 R13)

185/60 R13 – overall external circumference = 1734•7 mm (5•51% smaller than 155/82 R13)


175/65 R14 – overall external circumference = 1831•8 mm (0•22% smaller than 155/82 R13) [MG-F & MG-TF space saver spare]

175/55 R14 – overall external circumference = 1721•9 mm (6•21% smaller than 155/82 R13)

185/50 R14 – overall external circumference = 1698•3 mm (7•49% smaller than 155/82 R13)


185/65 R15 – overall external circumference = 1952•5 mm (6•35% larger than 155/82 R13) [Nigel’s preferred future choice]

185/60 R15 – overall external circumference = 1894•3 mm (3•18% larger than 155/82 R13)

185/55 R15 – overall external circumference = 1836•2 mm (0•02% smaller than 155/82 R13)

185/45 R15 – overall external circumference = 1720•0 mm (6•31% smaller than 155/82 R13)

195/45 R15 – overall external circumference = 1748•2 mm (4•78% smaller than 155/82 R13)


185/55 R16 – overall external circumference = 1916•0 mm (4•36% larger than 155/82 R13)

195/55 R16 – overall external circumference = 1950•6 mm (6•25% larger than 155/82 R13)

I would be extremely wary of using ultra-low-profile 45-Series tyres on classic cars like the Triumph Toledo & Dolomite, whose suspension was designed to work in series with the vertical “spring-stiffness” & “damping” of 80-Series or 70-Series radial-ply tyres.

185/45 R15 => sidewall height = 83•25 mm

195/45 R15 => sidewall height = 87•75 mm

Several years ago, I came across the following on-line technical article:

Steve LaFerre, "Bottoming Out: With Aspect Ratios, How Low is Really Too Low?”, Tire Review, 22nd May 2008.

http://www.tirereview.com/bottoming-out ... y-too-low/

« In my lifetime tire aspect ratios have ranged from an 85-series to a 25-series. Did you ever clean the whitewalls on a 1952 Chrysler Imperial? Be thankful you didn’t. That’s why I like the new lower aspect blackwall radials. Not only are they easier to clean, they are radials, they handle astoundingly well, they give me a lot more grins per mile, as well as a low-rolling resistance gain in miles-per-gallon. »

« But many of us wonder how low a tire’s aspect ratio can go before we hit the point of diminishing return. To Michelin’s way of thinking, 25% of a tire’s section width is going to yield an 83 millimeter sidewall. “For everyday street-use tires an 80 millimeter sidewall height is our threshold,” says Mark Ludlow, a tire engineer for Michelin. »

« “Anything under that size is built only for racing or show cars. But we feel any sidewall that falls under 65 millimeters is more about show than go,” he says. “Think about the tire as an elastic, deformable subject working hard during cornering with virtually no slip angle available for it to do its job. A tire built to that size is simply too rigid. »

« “When the height of a sidewall is under 80 millimeters it just can’t deliver a normal regime of a slip angle because there is no elasticity or deformity available in a severe handling environment. Put another way, there is simply too little sidewall real estate for the work required of the tire. »


Given that a tyre of 80 mm side-wall height is considered the absolute minimum, for a modern or ultra-modern road car that is designed for use with low-profile tyres, I surmise that tyres of 83~88 mm side-wall height, would be of significantly too low-profile for 1970s vintage classic cars like the Triumph Toledo & Dolomite. Not only would I expect the ride to be unduly harsh, but road holding on uneven road surfaces, with bumps, corrugations & potholes is likely to be compromised, as well as being more susceptible to wheel & tyre damage.

On my 1974 Triumph Toledo 1300 “HL Special”, I wasn’t really planning to use 55-Series or lower aspect-ratio tyres on any size of wheel and I cannot ever imagine substituting a 16 inch or larger diameter wheel. Given that I seldom do more than brake gently & infrequently, I see no useful purpose in modifying the hydraulic brake system, other than to convert from the original single-circuit to a late-model Triumph Dolomite 1300/1500/1500HL dual-circuit system, which won’t alter the front or rear suspension’s un-sprung weight.

Although I have acquired some 7 x 16 inch Mercedes C-Class alloy wheels for use on my 1973 VW “1600” Type 2 Westfalia Continental motor-caravan (based upon the VW Kombi Type 23-517 model, having front & rear axle load limits of 1020 kg & 1270 kg respectively) as a substitute for the original factory-fitted 5½ x 14 inch steel wheels & Michelin XZX 185 R14 Reinforced tyres. For medium to large sized commercial vans, 65-Series tyres on 16 inch wheels, has been virtually the de facto standard for the past ten years or more, and 80-Series commercial-van tyres for 14 inch wheels are becoming progressively rarer and relatively expensive!

Since I first started driving the Triumph Toledo in May 1975, it’s been exclusively shod with either 175 SR13 (i.e. 175/80 R13) or 185/70 R13 tyres, on 5½ x 13 inch alloy wheels, of either 21 mm or 35 mm wheel-offset, so I don’t know what it would be like to drive on factory-standard 4 x 13 inch steel wheels and 155 SR13 (i.e. 155/80 R13) tyres.

The “original” 175 SR13 (i.e. 175/80 R13) tyre size is something of an expensive rarity these days [MyTyres.com list only two options! | HI FLY 175/80 R13C 97/95R commercial-van tyres @ £46•99 each or Maxxis MA1 P175/80 R13 86S car tyres @ £107•89 each | neither is highly rated for fuel-economy or wet-weather performance ] and even the 185/70 R13 tyre size is far from common now and probably destined to become rarer in the coming years.

175/80 R13 – 86S or 175/80 R13C - 97/95R | 2 results

https://www.mytyres.co.uk/search?sortCo ... iews=false

185/70 R13 – 86 T | 17 results

https://www.mytyres.co.uk/search?sortCo ... iews=false

Given that most small to medium sized modern cars, are now equipped with either 15 inch or 16 inch wheels, it makes sense to substitute 15 inch wheels, for which there is likely to be much more choice of tyres in the coming years, before the use of petrol-engined cars is eventually outlawed.

When I get around to completing the Triumph Toledo projects, I have a set of seven, MG 2000 Maestro 5½ x 15 inch cross-lattice style alloy wheels [31 mm wheel-offset], to which I have the option of fitting 185/65 R15, 185/60 R15 or 185/55 R15 tyres, in conjunction with either a 4•11:1 or 3•89:1 final-drive ratio. Although there are a few 185/55 R15 tyres available in a T speed-rating, most are of either an H or V speed-rating, which would be undesirable (if for no other reason than rolling resistance) on a road-going car, that is unlikely to ever be driven at speeds in excess of 70 mph, and typically driven at 40~60 mph outside urban areas. There were more than twice as many options for 65-Series tyres than for 55-Series tyres!

Checking on MyTyres.com, I found the following options:

185/65 R15 – 88 T or 88 H or 92 T XL or 92 H XL | 290 results

https://www.mytyres.co.uk/search?sortCo ... iews=false

185/60 R15 – 84 T or 84 H / 88 T XL or 88 H XL | 209 results

https://www.mytyres.co.uk/search?sortCo ... ologation=

185/55 R15 – 82 T, 82H or 82V / 86 H XL or 86 V XL | 132 results

https://www.mytyres.co.uk/search?sortCo ... ologation=

Quote:
I've also been looking at tyres and I can easily get 185/60/15s in a range of makes and speed ratings for sensible money. Toyo Proxes CF2s are £52 a corner and Falken Sinceras are £58 a corner. There are no name specials for under £40 a pop but i'm not THAT hard up! The tyres on the Dolomega currently are 185/60/14s, so i'd basically be lifting the car a 1/2", but no other change to aspect ratio or compliance from what I now have. I already have an electronic speedo, so calibration is only a matter of a single measurement (rolling radius in inches) a couple of quick sums and punch the result into the speedo.

The Carledo ran on 195/50/15s and I had to relieve the arches a little bit to get them in, but a narrower, higher aspect tyre might negate that a bit.

According to the following references, the standard rim-widths for 195/50 R15, 185/55 R15, 185/60 R15 & 185/65 R15 tyres, are 6 inches, 6 inches, 5½ inches & 5½ inches respectively, so using the tyre-industry “rule-of-thumb”, I would expect the actual installed section-width of such tyres on a 5½ inch wide wheel, to be about 5 mm greater on average for either 60-Series or 65-Series tyres than for a 55-Series tyre.

The same argument also applies to installations on a 6 inch wide wheel, where in general, the installed section-widths of identical tyres of the same size, will be circa 5 mm larger on a 6 inch wide wheel than on a 5½ inch wide wheel. This is one of the reasons why I elected to use an MG 2000 Maestro 5½ x 15 inch wheel of 31 mm wheel-offset in preference to an MG 2000 Montego 6 x 15 inch wheel of 28 mm wheel-offset; which I anticipate will give about 5½ mm greater clearance between the tyre sidewall and the outboard areas of the rear wheel-arches.

Tire Specs Explained: Rim Width Range

http://www.tirerack.com/tires/tiretech/ ... techid=198

Tire Specs Explained: Measuring Rim Width

http://www.tirerack.com/tires/tiretech/ ... techid=199

Range of Wheel Sizes for Given Tyre Sizes

http://www.tyresizecalculator.com/tyre- ... calculator

Tyres: 195/50 R15 => Wheels: 15 x 5½ minimum | 15 x 6 standard | 15 x 7 maximum

Tyres: 185/55 R15 => Wheels: 15 x 5 minimum | 15 x 6 standard | 15 x 6½ maximum
Tyres: 185/60 R15 => Wheels: 15 x 5 minimum | 15 x 5½ standard | 15 x 6½ maximum
Tyres: 185/65 R15 => Wheels: 15 x 5 minimum | 15 x 5½ standard | 15 x 6½ maximum
Tyres: 185/70 R15 => Wheels: 15 x 4½ minimum | 15 x 5 standard | 15 x 6 maximum

Tyres: 185/70 R13 => Wheels: 13 x 4½ minimum | 13 x 5 standard | 13 x 6 maximum

There will be significant variations between different tyre brands, but one might expect on average to have about 2½ mm less clearance on either side of a 185/60 R15 tyre than a 185/55 R15 tyre, when mounted on the same wheel.

By similar arguments, one might expect on average to have about 2½ mm more clearance on either side of a 185/60 R15 tyre than a 195/50 R15 tyre, when mounted on the same wheel.

For more detail, refer to my earlier discussion as follows:

Board index » The Triumph Dolomite Club » Dolomite-related [Start here!] » MG-Rover-Austin Maestro or Montego alloy wheels for Triumph Toledo & Dolomite

https://forum.triumphdolomite.co.uk/vie ... 94#p321555

_________________
Regards.

Nigel A. Skeet

Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.

https://www.linkedin.com/profile/view?id=308177758

Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)

Onetime member + magazine editor & technical editor of Volkswagen Type 2 Owners' Club


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PostPosted:Sun May 22, 2022 8:25 pm 
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Joined:Sun Aug 21, 2011 4:12 pm
Posts:6581
Location:Highley, Shropshire
Just as an aside really and because I did it in the last few days, i've been having a fiddle with tyre sizes on SWMBO's Picasso which comes as standard with a 6x15 alloy wheel shod with 185/65/15s.

The fiddling came about largely because she experienced a road debris induced blowout on the n/s/r tyre last Sunday, right in the middle of the roadworks on the M5/M4 junction. The tyre was scrap with a 2" cut in the tread, fortunately (or more precisely, because I pay attention to such things) the spare tyre possessed both tread and air and the thread that lifts the underfloor spare into position was free and easy to use.

My son in law, who was driving at the time, (I was at home) was able to change the wheel with only one small hiccup, that being a serious design flaw by Citroen. The spare wheel is under the boot floor on a cradle that has to be lowered till it touches the ground, a narrow release aperture at best, made worse by the towbar the car is fitted with, the amount of weight in the car and MUCH worse by the stone flat left rear tyre. No sweat you'd think, just jack the car up till you can get it out. Until you learn that the jack is in a box INSIDE the spare wheel!!!!!

Bless them, old Bill turned up just as Andy was wrestling with this philosophical problem and used their trolley jack to get the car high enough to access the spare wheel (and the jack!!)

Somebody on Citroen's design team will get a slap upside the head if I ever meet him, no excuse for this, it's just pathetic!

Back to our fiddling. On Thursday last I had to drive to Litchfield to collect my new MGF wheels, which came complete with tyres in good condition (more on these later) and I dropped the now spare tyre at the local tyre shop to fit a replacement, collecting the finished product on the way home. At which point I noticed that both the FRONT tyres on the Picasso were badly worn on the inside edges. Now this is almost certainly MY fault. For last year's MOT I replaced a track rod end and I did the usual trick of replacing the new one up to the stop of the locknut which I had deliberately only released a minimum amount and wound the new balljoint up to the nut again, job done. I have tracking guages and always MEANT to check it, guess it slipped my mind!

Rather than spend another £130 on 2 more new tyres, I consulted with the guys and persuaded them to fit the 2 good 205/50/15s from the F wheels (which had been the rear tyres on the F and redundant for my Dolomega) onto the Picasso rims.

It doesn't LOOK that good, the arch gaps are a bit big, but grip, ride comfort and traction wise all seems fine, EXCEPT for 2 things, firstly the warning light comes on for the Elecronic Stability Program if I corner a bit too exuberantly, It's only done this previously when a rear tyre was almost flat, this brings in traction control and kills the throttle operation, secondly the swap has caused a massive 10% (optimistic) error in the speedo when it used to be more or less accurate (1mph optimistic @70mph) If it's had that much effect on the clock, it will have a similar effect on my fuel consumption (not that good at best, a Picasso LOOKS aerodynamic, but it really ISN'T) that I can ill afford.

So tomorrow i'll be swapping the 205/50s to the back and refitting correct sized tyres to the driving (and speedo sensing) axle!

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
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PostPosted:Wed May 25, 2022 5:09 pm 
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Determining Wheel-Offset
Quote:
I have not, so far, been able to find ANY aftermarket wheels available to buy at ANY price in 5.5 or 6 x 14" or 15" diameter and using the 95.25 PCD with an ET above 25. Bizzarrely, the best I could find is the MGF 6x15 in several different styles which I have recently discovered have an ET of 28, 6 whole mm better than my fake Minilites! I've been using these on the Carledo for 11 years! I don't really want to use 15s on this car as they necessitate 50 profile tyres which are not as compliant.
Various websites quote different values for MG-F & MG-TF and other wheel offsets, so a measured value is necessary, if the value is NOT clearly and unambiguously embossed on the wheel. Where or how did you learn that the MG-F’s 6 x 15 inch wheels have a wheel-offset of 28 mm, which is what I had come to suspect, but had yet to receive any verification!?!

The Internet websites of both Carl Salter and MGF Ultimate Engineering indicate that MG-F wheels have offsets in the range 30~35 mm, that I am inclined to disbelieve, which is why I am still patiently waiting to hear from anyone who has actually taken physical measurements & calculations to determine this (as described below) on the various styles of 15 inch & 16 inch, MG-F & MG-TF wheels

http://www.carlsalter.com/rover-wheel-fitments.html

http://www.mgf.ultimatemg.com/group2/su ... he_mgf.htm

On the Internet website of the Triumph TR Register, it is stated that Triumph TR7 wheels have a wheel-offset of 25 mm, whilst that of MG-F wheels have a wheel-offset of 20 mm.

Triumph TR7 / TR7 V8 and TR8 Buyers Guide

http://www.tr-register.co.uk/tr-buyers- ... -tr7v8-tr8

If the wheels are not stamped with their offset in mm (typically marked ET followed by a number), there is a simple way of measuring it using a centimetre & millimetre rule or tape measure, whose calibrations start exactly at the end (i.e. no space between end of rule or tape measure and the start of measurement section). This can still be done successfully to reasonable accuracy with the tyre still on.

1) Place the wheel flat on a level floor or table surface, with the outer section of the wheel (the part where one would fasten the wheel-bolts or nuts) facing upwards;
2) Measure vertically upward from the level surface to the wheel’s mounting face (the part which makes contact with the car’s wheel-hub);
3) Turn the wheel over so that the outer section of the wheel (the part where one would fasten the wheel-bolts or nuts) is facing downwards;
4) Again measure vertically upward from the level surface to the wheel’s mounting face (the part which makes contact with the car’s wheel-hub);
5) Subtract the second measurement from the first and divide the answer by 2. This final positive or negative number, is the wheel’s offset in mm.


Determining PCD – Pitch Circle Diameter

PCD – Pitch Circle Diameter is NOT usually marked on any wheels, but Triumph Toledo & Dolomite wheels have only four fixing holes to hold the wheel onto the car’s wheel-hub, so it’s easy to measure using an ordinary tape measure; preferably one calibrated in centimetres and millimetres. Various websites quote different values for MGF & MGTF wheel PCDs, so a measured value is necessary.

The centres of the four fixing holes, can be thought of as the corners of a square. To measure the PCD of a wheel with four fixing holes, one needs to measure the centre-to-centre distance between a pair of diagonally opposite holes. The diagonal passes over the centre of the large hole in the centre of the wheel. In effect, one is measuring the length of the diagonal, across the centre of the square.

Measuring the PCD of a wheel with an even-number of fixing holes is equally straightforward, but for a wheel with an odd-number of fixing holes (my 1973 VW Type 2 wheels have five fixing holes), the process involves knowledge of triangles, plus basic geometry & trigonometry, such as one would probably have studied for GCSE or GCE “O” Level Mathematics.

For greatest accuracy, it is best to make these measurements on the inside mounting face of the wheel, where it fits onto the car’s wheel-hub. It is too difficult to take accurate measurements on the outer face of the wheel, where the tapered wheel-fastening nuts are fitted.

It’s sometimes difficult to judge the exact position of a hole’s centre, so a more accurate measurement of equal value, is to actually measure from the innermost-edge of the left-hand hole, to the outermost-edge of the diagonally opposite right-hand hole.

_________________
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Nigel A. Skeet

Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.

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Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)

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PostPosted:Wed May 25, 2022 10:14 pm 
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Location:Highley, Shropshire
I've measured the JBW fake minilites and the ET is indeed 22, my new set of MGF alloys are marked 6x15 +28 the last figure I would assume is the ET (it's also written the same on the old MGF 5 spokes on the Carledo. Having now tried them on the car (rear only with 185/55 tyres) the difference in apparent offset seems to bear this out and a rough road test over several spots that caused graunching on the arches with the JBW wheels produced no such sound effects at considerably higher speeds with the F wheels.

So i'm happier than I was, i've already used the 205/50s on the Picasso (saving myself £100 in the process) I shall be swapping out the 185/55s for 185/60s for better compliance, a slight raise in overall ride height and because the 185/55s are clearly marked (and I kid you not!) LING LONG! And putting 185/60s on the now bare 2nd pair of wheels to complete the set. Think i'll be going for the Toyos (Proxes CF2s) again. They seem to suit the Carledo and last reasonably well for the amount of grip they generate.

I'm pretty pleased from the aesthetic angle too, I had severe doubts about the 5 spokes on the Carledo being "wrong for the car" and also because I think (or thought) that 4 studs with 5 spokes is, well, weird TBH. But I got used to them in time and when, some years later, I had opportunity to fit something more traditional, decided against it. 6 spokes with 4 studs seems more homogenous somehow, I think they'll be fine.

I'm also in the process of acquiring some stock Sprint rear springs and new shox, whilst I like my rear end soft, you can have too much of a good thing and the car reacts really badly to heavy loads in rear seat and boot. A little stiffer won't hurt the handling!

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
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PostPosted:Thu May 26, 2022 4:50 pm 
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Quote:
Just as an aside really and because I did it in the last few days, i've been having a fiddle with tyre sizes on SWMBO's Picasso which comes as standard with a 6x15 alloy wheel shod with 185/65/15s.

Rather than spend another £130 on 2 more new tyres, I consulted with the guys and persuaded them to fit the 2 good 205/50/15s from the F wheels (which had been the rear tyres on the F and redundant for my Dolomega) onto the Picasso rims.

It doesn't LOOK that good, the arch gaps are a bit big, but grip, ride comfort and traction wise all seems fine, EXCEPT for 2 things, firstly the warning light comes on for the Electronic Stability Program if I corner a bit too exuberantly, It's only done this previously when a rear tyre was almost flat, this brings in traction control and kills the throttle operation, secondly the swap has caused a massive 10% (optimistic) error in the speedo when it used to be more or less accurate (1mph optimistic @70mph) If it's had that much effect on the clock, it will have a similar effect on my fuel consumption (not that good at best, a Picasso LOOKS aerodynamic, but it really ISN'T) that I can ill afford.

So tomorrow i'll be swapping the 205/50s to the back and refitting correct sized tyres to the driving (and speedo sensing) axle!

Steve
185/65 R15 – external circumference = 1952•4 mm [Nigel’s preference for Triumph Toledo 1300 “HL Special” )

205/50 R15 – external circumference = 1840•9 mm (5•71% smaller than 185/65 R15)

Noting that the Citroën Picasso was specified with 185/65 R15 tyres at both the front & rear, substituting 205/50 R15 tyres at either the front or rear, to give either 185/65 R15 at the front & 205/50 R15 at the rear OR 205/50 R15 at the front & 185/65 R15 at the rear, is likely to change the front-rear balance of tyre “slip-angles”, under one or more conditions of constant velocity (i.e. constant speed & direction), acceleration, braking and cornering, and hence affect the under-steer and/or over-steer characteristics of the vehicle under these conditions.

https://en.wikipedia.org/wiki/Slip_angle

https://en.wikipedia.org/wiki/Slip_angle#Effects

https://suspensionsecrets.co.uk/tyre-slip-angle/

https://www.sciencedirect.com/topics/en ... teer-angle

https://www.sciencedirect.com/topics/en ... ngle-alpha

www.racelogic.co.uk/_downloads/vbox/App ... lained.pdf


https://en.wikipedia.org/wiki/Understeer_and_oversteer

https://www.mertonauto.com/oversteer-an ... the-limit/

mgf.ultimatemg.com/group2/suspension/chassis_and_handling/slip_angle.htm

https://www.tirereview.com/angled-appro ... ing-force/

I would anticipate that having 185/65 R15 at the front & 205/50 R15 at the rear, would tend to generally reduce over-steer & increase under-steer.

I would anticipate that having 205/50 R15 at the front & 185/65 R15 at the rear, would tend to generally reduce under-steer & increase over-steer.

From the mid-1970s onward, the legendary rear-engined, rear-wheel-drive Porsche 911, was renowned for its wayward handling characteristics, owing to extreme over-steer when driven hard. This was at least one of the reasons why in later years, wider, lower-profile tyres were fitted at the rear, and narrower, taller-profile tyres were fitted at the front. This was used in combination with much greater tyre pressures at the rear than at the front, which has long been recognised as one of the ways of combatting inherent over-steer characteristics.

Sometime since the late-1990s, I had noted that the VW Sharan, SEAT Alhambra and/or Ford Galaxy MPVs, were specified with the option of either 195/60 R16 or 215/55 R16 tyres on 16 inch wheels; which all had 5 x 112 mm PCD wheels in common with the 1971~79 VW 1600 & 17/18/2000 Type 2 Transporters.

Hence, I surmised that if I were to replace the standard 185/80 R14 Reinforced tyres on 14 inch wheels at front & rear, of my rear-engined, rear-wheel-drive 1973 VW “1600” Type 2 Transporter based motor-caravan, with 195/60 R16 tyres on 16 inch wheels at the front and 215/55 R16 tyres on 16 inch wheels at the rear, salvaged at a vehicle dismantler, from one or more of these VW, SEAT & Ford MPVs, this might be a reasonably effective & cost-effective way, of combatting the VW Type 2’s inherent over-steer characteristics, which are particularly & disconcertingly noticeable in gusting cross-winds, at road-speeds much in excess of 40~45 mph.

185/80 R14 – external circumference = 2047.0 mm

195/60 R16 – external circumference = 2011.8 mm (1•72% smaller than 185/80 R14)

215/55 R16 – external circumference = 2019.7 mm (1•33% smaller than 185/80 R14)

However, being of smaller external circumference than the factory-standard 185/80 R14 tyres, I was concerned that the resulting overall effective engine gearing provided by 215/55 R16 tyres, would be a poor match to my substitute 1911 cm³ displacement, circa 90~95 horsepower, modified, hybrid 1972 VW 412LE engine (i.e. VW Type 4 style, fuel-injected, air-cooled engine; originally of 1679 cm³ displacement), even with the substituted 1974~75 VW 1800 Type 2 transaxle (a 1976~79 VW 2000 Type 2 transaxle might have been better, but were not readily available!?!). The other concern was whether the wheels & tyres from the VW, SEAT & Ford MPVs would be of appropriate wheel-offset & adequate tyre load rating.

_________________
Regards.

Nigel A. Skeet

Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.

https://www.linkedin.com/profile/view?id=308177758

Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)

Onetime member + magazine editor & technical editor of Volkswagen Type 2 Owners' Club


Last edited by naskeet on Thu May 26, 2022 5:48 pm, edited 1 time in total.

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PostPosted:Thu May 26, 2022 4:53 pm 
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Although I have primarily focused my attention on the use of 185/65 R15, 185/60 R15 & 185/55 R15 tyres with 5½ x 15 inch wheels, one also has the option of using 175/65 R15, 175/60 R15 & 175/55 R15 tyres, which would also be suitable for use with this wheel size.

155 R13 => 155/83 R13 – overall external circumference = 1845•6 mm
155 R13 => 155/82 R13 – overall external circumference = 1835•9 mm
155 R13 => 155/80 R13 – overall external circumference = 1816•4 mm

175/65 R15 – overall external circumference = 1911•7 mm (4•13% larger than 155/82 R13)

175/60 R15 – overall external circumference = 1856•7 mm (1•13% larger than 155/82 R13)

175/55 R15 – overall external circumference = 1801•7 mm (1•86% smaller than 155/82 R13)

185/65 R15 – overall external circumference = 1952•5 mm (6•35% larger than 155/82 R13)

185/60 R15 – overall external circumference = 1894•3 mm (3•18% larger than 155/82 R13)

185/55 R15 – overall external circumference = 1836•2 mm (0•02% larger than 155/82 R13)

Hence, if one seeks to closely match the external circumference of an original factory-fitted 155 SR13 (i.e. 155/82 R13) radial-ply tyre on 4J x 13 inch or 4½J x 13 inch steel wheels, then either a 175/60 R15 or 185/55 R15 tyre on a 5½ x 15 inch wheel would seem to be two of the best options.

However, there appears to be less choice re 65-Series, 60-Series & 55-Series tyres of nominally 175 mm section-width, compared to those of 185 mm section-width, and I have the subjective impression, that on average, the narrower tyres are more expensive. There are more than three times as many options re 65-Series tyres compared to either 60-Series or 55-Series tyres.

Checking on MyTyres.com, I found the following options:

https://www.mytyres.co.uk/

175/65 R15 – 84 T or 84 H / 88 T XL or 88 H XL | 146 results

https://www.mytyres.co.uk/search?sortCo ... eTypes=OFF

175/60 R15 – 81T or 81 H or 81 V / 85 H XL | 38 results

https://www.mytyres.co.uk/search?sortCo ... eTypes=OFF

175/55 R15 – 77 T, 77 H or 77 V / 81 T XL | 44 results

https://www.mytyres.co.uk/search?priceC ... 15&season=

_________________
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Nigel A. Skeet

Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.

https://www.linkedin.com/profile/view?id=308177758

Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)

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PostPosted:Sat May 28, 2022 5:46 pm 
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Quote:
I've also found a set of F alloys on ebay in a style I quite like (6 blocky, parallel spokes) WITH tyres for £120. The tyres have decent tread but are the usual MGF combo of 2 x 185/55 and 2 x 205/50. But I could TRY the 185/55s on the back and see how it goes, before I spend money on tyres, something I never thought to do on the Carledo in years gone by. Might also be possible to shave a couple of mm off these too.

I'm not terribly worried about the weight of the F rims, it didn't seem to noticeably upset the Carledo, but then again I expected harsh and noisy from that track focused car, so wasn't surprised when I got it! But it didn't have bump steer or any of the other nasty side effects of too high an unsprung weight.

According to the information at the following Internet website links, the 6 x 15 inch MG-F & MG-TF alloy wheels, seem to weigh-in at around 7•5 ~ 7•6 kg, but the weights of some wheels are not listed.

http://www.mgf.ultimatemg.com/group2/su ... he_mgf.htm

So far, I have yet to weigh my sets of five bare, tyreless 6 x 15 inch MG 2000 Montego & 5½ x 15 inch MG 2000 Maestro cross-lattice style wheels, but for the purposes of initial comparison, of combined wheel & tyre weights, which is probably more important, I did weigh the following on my decades old, “less-than-accurate” bathroom scales.

Dolomite Sprint 5½J x 13 inch wheels & Firestone S211, 185/70 R13 (circa 6 mm tread): weight = 2 st 0 lbs = 28 lbs = 12•7 kg

MG Maestro 5½J x 15 inch wheel & Michelin MXV2, 185/55 R15 tyre (circa 2½ mm tread): weight = 2 st 2 lbs = 30 lbs = 13•6 kg

MG Maestro 5½J x 15 inch wheel & Cheng Shin Maxxis, 185/55 R15 tyre (circa 6~7 mm tread): weight = 2 st 6 lbs = 34 lbs = 15•4 kg

It’s interesting to note the apparent 1•8 kg weight difference, between the nearly four-fifths worn MXV2 tyre and the nearly new Maxxis tyre. If one were to substitute either 185/60 R15 or 185/65 R15 tyres, then one would expect the wheel & tyre combinations to be somewhat heavier, owing to the increased quantity of textile-reinforced rubber. Compared to the weight of the heavy, rear live-axle, this increase would be relatively insignificant, but it remains to be seen what effect this will have on the front suspension.

When I worked at the Celcon Block Company’s R &D laboratory during the late 1980s, I used a 2 tonne capacity balance, to regularly weigh two-metre-square specimen masonry-wall samples in RSJ frames, to a precision of ± 0•01 kg (to determine equilibration of moisture content), so using my ancient bathroom scales which struggle to weigh wheel & tyre combinations to a precision of barely ± 0•25 kg, with any reasonable degree of repeatability, is a major let down!

Quote:
I've measured the JBW fake minilites and the ET is indeed 22, my new set of MGF alloys are marked 6x15 +28 the last figure I would assume is the ET (it's also written the same on the old MGF 5 spokes on the Carledo. Having now tried them on the car (rear only with 185/55 tyres) the difference in apparent offset seems to bear this out and a rough road test over several spots that caused graunching on the arches with the JBW wheels produced no such sound effects at considerably higher speeds with the F wheels.

So i'm happier than I was, i've already used the 205/50s on the Picasso (saving myself £100 in the process) I shall be swapping out the 185/55s for 185/60s for better compliance, a slight raise in overall ride height and because the 185/55s are clearly marked (and I kid you not!) LING LONG! And putting 185/60s on the now bare 2nd pair of wheels to complete the set. Think i'll be going for the Toyos (Proxes CF2s) again. They seem to suit the Carledo and last reasonably well for the amount of grip they generate.

I'm pretty pleased from the aesthetic angle too, I had severe doubts about the 5 spokes on the Carledo being "wrong for the car" and also because I think (or thought) that 4 studs with 5 spokes is, well, weird TBH. But I got used to them in time and when, some years later, I had opportunity to fit something more traditional, decided against it. 6 spokes with 4 studs seems more homogenous somehow, I think they'll be fine.

I was pleased to learn that you have NOT so far experienced any interference or rubbing problems with the 6 x 15 inch MG-F six-spoke wheels & Linglong brand 185/55 R15 tyres! However, this does not mean that this would still be true if you substituted another brand of 185/55 R15 tyres or any brand of 185/60 R15 tyres! I shall file away for future reference, the information about the 6 x 15 inch MG-F alloy wheels having a wheel-offset of 28 mm, in common with 6 x 15 inch MG 2000 Montego lattice style alloy wheels

Keep in mind, that on average, 185/60 R15 tyres will have a circa 5 mm greater installed section-width than 185/55 R15 tyres, that are mounted on the same wheels. Also keep in mind, that the installed section-width of tyres, mounted on wheels of “standard” or “measuring” width, can vary considerably between different tyre manufacturers & brands, so a tyre of 185 mm nominal section-width, might conceivably be 185 ± 5 mm. Both of these factors have previously been discussed in the following post:

Board index » The Triumph Dolomite Club » Dolomite-related [Start here!] » MG-Rover-Austin Maestro or Montego alloy wheels for Triumph Toledo & Dolomite

https://forum.triumphdolomite.co.uk/vie ... 72#p319994

Although the 185/55 R15 tyres that came on my first set of two MG 2000 Maestro 5½J x 15 inch wheels have the same nominal section-width (i.e. 185 mm) as the 185/70 R13 tyres on my Triumph Dolomite Sprint 5½J x 13 inch wheels, the actual installed tyre section-widths (as measured by me using a tape measure in conjunction with a builder’s long spirit level as a straight edge) proved to be noticeably different!

Measuring the section-widths of one of the Firestone S211, 185/70 R13 85T tyres (made in France & South Africa) on the Dolomite Sprint wheels, plus the Michelin MXV2, 185/55 R15 81V tyre (made in West Germany) and Cheng Shin Maxxis MA-551, 185/55 R15 82V tyre (made in PRC – Peoples’ Republic of China; aka Taiwan or Formosa), on the MG Maestro wheels, produced the following results:

Firestone S211, 185/70 R13 – Installed tyre section-width = 189¼ ± ¼ mm

Michelin MXV2, 185/55 R15 – Installed tyre section-width = 189¾ ± ¼ mm

Cheng Shin Maxxis MA-551 185/55 R15 – Installed tyre section-width = 193¼ ± ¼ mm

I shall probably pass on the new or nearly-new (circa 6~7 mm tread-depth) Maxxis185/55 R15 tyre to some deserving soul; not because it is of “Chinese” manufacture, but because I doubt that I shall wish to use 55-Series tyres.

Before you splash out any more money, it might be useful to first obtain a measure of much clearance you have with your present Linglong brand 185/55 R15 tyres, using some thin strips of material (e.g. 3 mm plywood) in the manner of oversized feeler gauges, which should hopefully enable you to assess how much leeway you have.

The first time I saw those five-spoke MG-F wheels with four fixing studs & nuts on your Triumph Toledo “Carledo”, I too thought they looked weird! For the same reason, I cannot conceive why there is an eleven-spoke MG-F or MG-TF wheel, rather than one with twelve spokes! I’m not a great fan of the various manifestations of the six-spoke MG-F & MG-TF wheels either, but given that six & four share a common factor of two, they don’t look quite so incongruous! If I really had to choose an MG-F or MG-TF wheel, it would probably be of the eight-spoke “Minilite” style, for which eight is a multiple of four, or the so-called “hair-pin” style, provided the number of spokes was a multiple of four.

I have never heard of “LING LONG” tyres before, but as the name suggests they are of Chinese origin; in this case mainland communist China rather than PRC – Peoples’ Republic of China. There are some good engineers in mainland China, some of whom I met at Cranfield during the early-1980s, when I was a postgraduate engineering student there.

I’m not sure about the quality of Chinese car tyres, but from what I have read recently, Shandong Linglong Tyre Co. Ltd. who make the Linglong brand tyres, seem to be a major industrial company with 17,000 employees and several factories, and sell tyres of various types in 160 countries. I looked at the Linglong selection of car tyres in America, of which there seem to be several types. There also seem to be references to Linglong tyres on some of the British tyre retailers’ Internet websites, although I have yet to identify any which stock Linglong tyres in the 185/55 R15, 185/60 R15 or 185/65 R15 sizes.

https://www.mytyres.co.uk/Linglong-tyres.html

https://www.tirendo.co.uk/tyre/brand/Linglong

https://www.easywheels.co.uk/linglong-tyres/

https://www.linglongtire.com

https://www.linglongtire.com/passenger-tires/

https://www.linglongtire.com/about-us/

There seem to be several Chinese and Taiwanese tyre brands, making inroads into the British, European & North American market; many of which I have found listed on the Internet websites of British tyre-retailers.

Top Ten Chinese Tyre Brands, Trojan Ltd, 13th January 2020

https://www.trojanlimited.com/top-ten-c ... re-brands/

Tyre Manufacturers and Companies

https://en.wikipedia.org/wiki/List_of_t ... %20rows%20

_________________
Regards.

Nigel A. Skeet

Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.

https://www.linkedin.com/profile/view?id=308177758

Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)

Onetime member + magazine editor & technical editor of Volkswagen Type 2 Owners' Club


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PostPosted:Mon May 30, 2022 6:01 pm 
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Future Club member hopefully!

Joined:Tue May 06, 2014 3:38 pm
Posts:427
Location:South Benfleet, Essex
Three Wheels on a Four-Wheeled Car!?!
Quote:
The original plan for the Dolomega was to retain the original Sprint wheels to enhance the "sleeper look". This went out the window fairly quickly as it only came with 3 Sprint rims, all in awful condition.

I don’t think I have ever seen a car being driven on only three wheels before, with the possible exception of a circa 1960s vintage Citroën DS, whose then revolutionary suspension system made this possible! :shock: :?

Are you implying that the car came fitted with a set of four or five 4½ x 13 inch steel wheels & 155 SR13 standard-profile tyres, but was also supplied with an incomplete set of only three, rather than a complete set of five 5½ x 13 inch Dolomite Sprint alloy wheels!?! After all, it would have been rather strange to acquire a car which had only three wheels in total!

When my father bought the 1974 Triumph Toledo 1300 in May 1975, it came equipped with five 5½ x 13 inch Cosmic alloy wheels, which in July 1996, I swopped for a set of five 5½ x 13 inch Dolomite Sprint alloy wheels; that in due course will be swopped for a set of five 5½ x 13 inch MG 2000 Maestro alloy wheels, with two 5½ x 13 inch MG 2000 Maestro alloy wheels in reserve, in case any get damaged by our now atrocious potholed roads, which are unlikely to be adequately repaired or resurfaced any time soon.

Given that the Triumph Dolomite Sprint has been obsolete for more than 40 years, I would think it prudent for anyone whose Triumph Toledo or Dolomite is equipped with Dolomite Sprint wheels, to have at least one additional spare, in case one of the wheels is damaged in service, or to enable tyre rotation if one uses modern directional tyres.

Spare Tyre “Provision” when Substituting Non-Standard Wheels & Tyres
Quote:
Just as an aside really and because I did it in the last few days, i've been having a fiddle with tyre sizes on SWMBO's Picasso which comes as standard with a 6x15 alloy wheel shod with 185/65/15s.

The fiddling came about largely because she experienced a road debris induced blowout on the n/s/r tyre last Sunday, right in the middle of the roadworks on the M5/M4 junction. The tyre was scrap with a 2" cut in the tread, fortunately (or more precisely, because I pay attention to such things) the spare tyre possessed both tread and air and the thread that lifts the underfloor spare into position was free and easy to use.
From your account of events, I surmise that the 185/65 R15 tyre with “2 inch cut in the tread” on the Citroën Picasso, would have been unserviceable and/or extremely hazardous over any distance, even with the use of high-pressure aerosol injected sealant, that now seems to be the modern replacement option, for even the less than ideal, limited-service, space-saver, spare-wheel & tyre combination!?!

https://www.theaa.com/driving-advice/sa ... d-sealants

https://www.theaa.com/driving-advice/sa ... are-wheels

That being the case, I presume you would not wish to risk becoming stranded for wont of a spare wheel & tyre, if your Triumph Dolomite “Dolomega” were to suffer a similar fate, owing to the lack of a spare, six-spoke 6 x 15 inch MG-F alloy wheel & 185/60 R15 tyre or at least a “space-saver” spare wheel & tyre of appropriate external radius and circumference, with compatible wheel nuts, to enable one to drive home.

If one chose to have a “space-saver” spare wheel & tyre, there is the challenge of finding a suitable wheel & tyre combination of appropriate external radius and circumference (about 3•2% larger than a 155/82 R13 tyre), that would be lighter and take up less space (i.e. be narrower; having a tyre of smaller installed section-width) in the spare-wheel well than a six-spoke 6 x 15 inch MG-F alloy wheel & 185/60 R15 tyre.

185/60 R15 – overall external circumference = 1894•3 mm (3•18% larger than 155/82 R13)

155 R13 => 155/82 R13 – overall external circumference = 1835•9 mm

165 R13 => 165/82 R13 – overall external circumference = 1866•7 mm (1•68% larger than 155/82 R13)

175/65 R14 – overall external circumference = 1831•8 mm (0•22% smaller than 155/82 R13) [MG-F & MG-TF space saver spare]

185/65 R14 – overall external circumference = 1872•7 mm (3•14% larger than 155/82 R13)

175/70 R14 – overall external circumference = 1886•8 mm (2•77% larger than 155/82 R13)

185/70 R14 – overall external circumference = 1930•8 mm (5•17% larger than 155/82 R13)

155 R14 => 155/82 R14 – overall external circumference = 1896•3 mm (3•29% larger than 155/82 R13)

135/80 R15 – overall external circumference = 1875•5 mm (2•16% larger than 155/82 R13) [used on Citroën 2CV I think!?!]

155/70 R15 – overall external circumference = 1878•7 mm (2•33% larger than 155/82 R13)

165/70 R15 – overall external circumference = 1922•7 mm (4•73% larger than 155/82 R13)

Having the same nominal 185 mm section-width, a 185/65 R14 tyre would offer little if any advantage and a 175 mm section-width, a 175/70 R14 tyre wouldn’t be much better, but a standard-profile 155 R14 (i.e. 155/80 R14 or 155/82 R14) tyre, if it and a suitably sized wheel (e.g. 14 x 4 inch, 14 x 4½ inch or 14 x 5 inch) exists, would appear to be an almost ideal, well matched option. Whether a suitably narrow 14 inch wheel from an Austin-Rover Maestro or Montego exists, I don’t yet know.

http://www.wheel-size.com/size/

Range of Wheel Sizes for Given Tyre Sizes

http://www.tyresizecalculator.com/tyre- ... calculator

Range of Tyre Sizes on Given Wheel Sizes

http://www.tyresizecalculator.com/tyre- ... calculator

_________________
Regards.

Nigel A. Skeet

Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.

https://www.linkedin.com/profile/view?id=308177758

Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)

Onetime member + magazine editor & technical editor of Volkswagen Type 2 Owners' Club


Last edited by naskeet on Wed Jun 01, 2022 5:50 pm, edited 2 times in total.

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