MG-Rover-Austin Maestro or Montego alloy wheels for Triumph Toledo & Dolomite

[naskeet]

Various topic threads on this and other forums, suggest the use of MG-F & MG-TF 6Jx15 inch alloy wheels with 4 x 3¾ inch (i.e. 4 x 95•25 mm) PCD – pitch circle diameter, for the Triumph Toledo & Dolomite.

Board index » The Triumph Dolomite Club » Dolomite-related [Start here!] » MGF WHEELS

viewtopic.php?f=4&t=33153

Board index » The Triumph Dolomite Club » Dolomite-related [Start here!] » Alternative Wheels

viewtopic.php?f=4&t=25854

Board index » The Triumph Dolomite Club » Dolomite-related [Start here!] » Alternative alloy wheels

viewtopic.php?f=4&t=1030

Although some of the following Internet links suggest that the various MG-F & MG-TF alloy and steel wheels (i.e. 6J x 15 inch alloy, 7J x 16 inch alloy and 5½J x 14 inch steel) have wheel-offsets in the range 18~30 mm or 30~35 mm, I have reason to suspect that the offset of at least some of the available 6J x 15 inch alloy wheels might actually be 28 mm, which is 7 mm less than the 35 mm offset, of the Triumph Dolomite Sprint’s factory-fitted 5½J x 13 inch GKN alloy wheels.

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

https://www.carlsalter.com/mg-rover-wheel-fitments.html

Although the Carl Salter website incorporates a lot of “information” about PCD, offset and centre-bore about wheels for many vehicle marques & models, I am aware that at least some of this information is incorrect, based upon my existing knowledge about specific vehicles; something which does not inspire confidence!

It is this website which declares the 1996 onward MG-F to have wheels of 18~30 mm offset and a 4 x 3¾ inch (i.e. 4 x 95•25 mm) PCD for the Rover 100, 114, 214, 220, 416 & 420, which I very much doubt!

MG-F: 1995~2002 (28 mm offset stated for 15 inch wheels)

https://www.wheel-size.com/size/mg/f/

https://www.wheel-size.com/size/mg/f/1995/

https://www.wheel-size.com/size/mg/f/2002/

MG-TF: 2002~2011 (28 mm offset stated for 15 & 16 inch wheels)

https://www.wheel-size.com/size/mg/tf/

https://www.wheel-size.com/size/mg/tf/2002/

https://www.wheel-size.com/size/mg/tf/2011/

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

« PCD: 95.25 mm »
« Offset: 30 - 35 mm »
« Centre bore: 56.6 mm »
« 15" wheels: 6J 15 »
« 16" wheels: 7J 16 »
« Spare: 5.5J 14 »
« Wheel nut torque: 90 Nm »

When in May 1975, my father bought our second-hand, ex-demonstration, four-door, 1974 Triumph Toledo 1300 (registered in mid-November 1974, to Mann & Egerton, the local Rover & Triumph dealership), it had already been customised to some extent.

Board index » The Triumph Dolomite Club » Dolomite-related [Start here!] » 40+ Years With A 1974 Triumph Toledo 1300 “HL”

viewtopic.php?f=4&t=29933

This included the substitution of Cosmic 5½ x 13 inch aluminium-alloy wheels (21 mm offset) and 175SR13 radial-ply tyres (not 175/70 SR13) in place of the original factory-fitted steel wheels and associated tyres, which were presumed to be 4J x 13 inch steel wheels with 155 SR13 radial-ply tyres.

In the 1972 brochure, the following Cosmic LM25 aluminium-alloy wheels are listed for the Triumph Herald, Vitesse, Spitfire, GT6, Toledo & Dolomite, requiring wheels having a PCD – pitch circle diameter with four fixing holes, of 4 x 3¾ inch (i.e. 4 x 95•25 mm); with the caveat that use of the 6 x 13 inch wheels might require bodywork modifications.

Archived 1972 brochure of after-market Cosmic aluminium-alloy wheels

http://mk1-performance-conversions.co.u ... ls1972.pdf

Noting the various forum members’ comments about Toledo and/or Dolomite rear wheel-arch interference problems, when using MG-F & MG-TF, 6J x 15 inch alloy wheels, together with warnings in the 1972 Cosmic sales brochure, about possible interference when using 6 x 13 inch Cosmic alloy wheels, I am wary of substituting any 6 inch wide wheels.

The following website link gives information pertaining to alternative 13, 14, 15 & 16 inch wheel & tyre combinations for the Triumph Dolomite Sprint, limited to those with an external rolling-circumference within +3% & -2% of that of the factory-standard 175/70 R13 tyres. Some of the information given therein also contributed to my wariness!

http://www.automobile-catalog.com/tire/ ... print.html

When the second set of 175 SR13 tyres on the Cosmic wheels (21 mm offset) were later replaced by Firestone S211, 185/70 R13 tyres, I experienced rubbing on the outboard sidewalls of the rear tyres, whenever carrying rear-seat passengers or heavy loads such as paving slabs or concrete building blocks in the boot.

This sidewall rubbing ceased to happen when I later substituted Triumph Dolomite Sprint 5½J x 13 inch GKN alloy wheels (35 mm offset) to which I had transferred the existing Firestone S211, 185/70 R13 tyres.

Various observations made by forum members in the following topic thread about interference problems and associated outboard sidewall rubbing, when using MG-F or MG-TF 6J x 15 inch alloy wheels, which I suspect have a 28 mm offset (contrary to what some Internet website links suggest!), prompted me to seek an alternative, because I wanted to avoid significantly modifying my Toledo’s rear wheel-arches if at all possible.

Board index » The Triumph Dolomite Club » Dolomite-related [Start here!] » MGF WHEELS

viewtopic.php?f=4&t=33153

I've got no measurements to speak of, but having fitted and run MGF 6x15s for some time, with a variety of tyre sizes I can say this:-

On the front they fit fine and work with either 185/55 or 195/50s. No interference detected under any conditions, even with the suspension lowered beyond the realms of reason (this was not deliberate, at one point in time when my new springs were bedding in and settling, I let it get VERY low before resetting my ride height adjustable shox)

The rear is a different matter, I tried the car initially on 205/50s and these interfered rather badly with the outer arch, even at stock ride height or a bit over, though they missed the inner arch by the narrowest of margins.

I have now settled on 195/50s. These still interfere with a standard arch a bit under extreme cornering conditions. Rather than go any narrower on rear tyres, I gave up at this point and turned up the rear arch lips. Several folk have asked why I didn't try the 185/55s that I had available on the rear. The simple answer is that it never occurred to me to try! And now trying is pointless because I have turned up the lips and all is well!

Steve

I have the 15" MGF alloys with 185/55/15 tyres, and I had to trim the rear arches back to nothing.

From what I have read on the subject of wheels and tyres, fitting the same individual tyre to a 6 inch wide wheel rim, will increase the tyre’s actual section-width by approximately1/5-inch (i.e. 5•08 mm) compared to what it would be on a 5½-inch wide wheel rim.

Assuming the MG-F or MG-TF 6J x 15 inch alloy wheels do have a 28 mm offset, then the tyre’s outboard sidewall would be circa 5•5 mm [i.e. (½ x 5•08 mm) + (31 mm – 28 mm) closer to the outboard lip of the wheel-arch, than if it were fitted to an MG Maestro 5½J x 15 inch alloy wheel with 31 mm offset.

[naskeet]

Using the Triumph Toledo’s & Dolomite’s 4 x 3¾ inch (i.e. 4 x 95•25 mm) PCD – pitch circle diameter, as the principal search criterion, I identified various potential donor car marques & models, as potential sources of second-hand 14 inch or 15 inch alloy wheels for my Toledo, but the information quoted on different Internet websites was as inconsistent and potentially incorrect as it had been for MG-F & MG-TF wheels.

Board index » The Triumph Dolomite Club » Dolomite-related [Start here!] » wheel sizes PCD?

viewtopic.php?f=4&t=18366

Triumph Torque > Chit Chat Boards > Technical Chit-Chat > Triumph PCD & Suitable Wheels

http://club.triumph.org.uk/cgi-bin/foru ... 197304398/

General search re PCD

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

Specific search using 4 x 3¾ inch (i.e. 4 x 95•25 mm) PCD

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

More specific search using 4 x 3¾ inch (i.e. 4 x 95•25 mm) PCD and 56•6 mm centre-bore

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

http://www.wheelfitment.eu/PCD/4x95.25/56.6.html

Caterham 7 Classic (1992~1998) - 15 mm offset
Lotus Elise S1 (1996~2001) - 10 mm offset
Lotus Exige S1 (2000~2004) - 38 mm offset
Rover MGF Roadster (1996~2006) - 28 mm offset

Given that wheel-offsets outside a certain range of values would be impractical, unless one either machined the wheel’s mounting face or used spacers as appropriate, this effectively eliminated the various Lotus car models with appropriate PCD (i.e. 1996~2001 Lotus Elise S1 – 10 mm wheel-offset | 2000~2004 Lotus Exige S1 – 38 mm wheel-offset) as possible donors; assuming the information was accurate.

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

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

Despite my misgivings, 14 or 15 inch alloy wheels from the MG Maestro, MG Maestro Turbo MG Montego or MG Montego Turbo seemed promising.

MG-Maestro: 1983~1990

https://www.wheel-size.com/size/mg/maestro/

https://www.wheel-size.com/size/mg/maestro/1983/

https://www.wheel-size.com/size/mg/maestro/1990/

MG-Montego: 1985~1991

https://www.wheel-size.com/size/mg/montego/

https://www.wheel-size.com/size/mg/montego/1985/

https://www.wheel-size.com/size/mg/montego/1991/

Steel wheels from the Austin-Rover Maestro and/or Montego, might also be an option worth considering.

https://www.wheel-size.com/size/rover/maestro/

https://www.wheel-size.com/size/rover/montego/

The 15 inch wheels of cross-lattice style in silver or white were quite attractive, and were a standard factory-fitment to the 2•0 litre models.

Ignoring the 4 fixing holes, the cross-lattice pattern has 20 degrees of rotational symmetry and given that 4 and 20, have 4 as the HCF (i.e. highest common factor), the overall wheel design has 4 degrees of rotational symmetry and 4 degrees of mirror symmetry, which are desirable attributes contributing to the attractiveness of a wheel. Sadly, many of the factory-fitted wheel designs for the MG-F & MG-TF do not share these attributes; especially those of 5-spoke & 6-spoke configuration.

MG Maestro or Montego 15 inch cross-lattice style wheels



I felt they wouldn’t look out of place on a Triumph Toledo 1300 “HL Special” and seemed more appropriate than the various styles that were factory-fitted to the MG-F & MG-TF.

Having little faith in the published data, my only recourse was to have the wheels’ offset and other specifications determined from information embossed on the wheels themselves or where practical, determined directly by measurement and calculation.

Over a period of several months, during 2016 & 2017, I followed up on sporadic listings on British E-bay and Gumtree, of MG Maestro and/or Montego wheels, for which some vendors were asking horrendously expensive “buy-it-now prices or starting-bid prices which already exceeded my budget.

However, during those months, I was able to glean the important information I sought about part numbers, rim-width, offset, maximum-load rating and fixing-stud & nut size, together with gaining some insight into the tyre sizes fitted to them. In some cases, the required information could be gained from published details or by close examination of the photographs which accompanied the listing. Otherwise, I sent a detailed list of questions to the vendors, who had inadequately described the items they had put up for sale.

Whatever happened, I was determined NOT to buy any wheels, whose specifications were uncertain. Having no personal transport available to me, I was limited by the need to have any wheels that I purchased delivered by courier or collected by my local friend who had a Ford C-Max from which the rear seats could be readily removed.

Finally, in March 2017, a pair of MG Maestro 5½J x 15 inch lattice-style alloy wheels (Part No. NAM 9101 | 415 kg maximum-load rating | 31 mm offset – marked on wheel, but I also later checked this by measurement & calculation) with 185/55 R15 tyres, were listed on E-bay at a starting-bid price of only £10•00, and much to my surprise, I won the auction with a bid of just £10•50; having previously clarified with the vendor that he would be willing to have them collected by UPS from Surrey and delivered to my home on Canvey Island at a cost of £13•73.

Both of these wheels featured the following markings surrounding the flat portion that abuts the car’s wheel-hub:

MADE IN BRITAIN

X-RAY PWE D 91 HT

MAX LOAD 415 KG

P. TEST 5•5Jx15CH31

NAM 9101 DATE/MELT

The two tyres are very different. One is a Michelin MXV2, 185/55 R15 81V, made in West Germany, with very little remaining tread depth (probably about 2½ mm), so would only really be suitable as an interim get-you-home spare. Noting that the unification of West & East Germany occurred in October 1990, I suspect this might be one of the original tyres that was factory-fitted to the car. The other, is what appears to be a nearly-new Cheng Shin Maxxis, 185/55 R15 82V, made in Taiwan, with a substantial tread-depth (probably about 6~7 mm).

Given that a factory-standard Triumph Toledo 1300 could barely reach 85 mph downhill with a tail-wind, even a T-speed-rated tyre is significantly over-rated so a V-speed-rated tyre would be grossly over-rated and have a greater rolling resistance!

Ultimately, I wanted a complete set of at least SIX matching wheels, so that I would have a matching spare in the boot, together with at least one spare-spare in the garage, in case a wheel was damaged beyond repair at some time in the future, during an encounter with a pothole, road debris or kerb.

If I could not obtain symmetrical and/or non-directional tyres, then having at least six wheels would allow me to have three right-handed wheel & tyre assemblies and three left-handed wheel & tyre assemblies, which could be rotated in sets of three to wear out complete sets of six tyres. I see no economic purpose in having one or more spare tyres that seldom if ever get used, but still deteriorate with age (n.b. six years from date of manufacture, is the estimated lifespan of a modern tyre) and periodically need to be replaced!

I surmised that the majority of people wishing to buy such wheels, probably seek either a set of four or five wheels (to upgrade from another type of wheel), or just a single wheel (to replace an identical damaged wheel or provide a matching spare, in place of a “space-saver” wheel. Hence, I was on the lookout for partial sets of either two or three matching wheels, which I hopefully might be able to acquire at similar “bargain-basement” prices! Sadly, I never found any more partial sets.

Several vendors were decidedly uncooperative with regard to identifying the technical specifications of the MG Maestro/Montego wheels they had listed for sale and more than nine more months passed, before I found any more MG Maestro 5½J x 15 inch cross-lattice style alloy wheels with 31 mm offset, which were clearly identifiable as such!

Finally, in December 2017, I purchased a set of five MG Maestro 5½J x 15 inch cross-lattice style alloy wheels (Part No. NAM 9101 | 400 kg maximum-load rating – 15 kg less than the first pair | 31 mm offset – marked on wheel) without tyres for £90, from a vendor in Yorkshire, but it took some hard-nosed negotiation to persuade him to package them appropriately in sets of two and three, for collection and delivery by UPS at optimal cost.

All five of these MG Maestro wheels featured the following markings surrounding the flat portion that abuts the car’s wheel-hub:

F 89 H T MAX LOAD 400 KG P. TEST

5•5Jx15CH31 NAM 9101 DATE/MELT

MADE IN BRITAIN E.I.F. X-Ray

Other Embossed Markings are 5025B XHT P plus something I can't read

A maximum load rating of 400 or 415 kg per wheel (1600 or 1660 kg for four wheels), should be more than adequate for a 4-door Triumph Toledo 1300, whose maximum all-up laden weight is stated to be 1265 kg.

During my long wait between March & December 2017, I was beginning to doubt whether I would find any more MG Maestro 5½J x 15 inch cross-lattice style alloy wheels with 31 mm offset, so I resorted to buying a set of five MG Montego 6J x 15 inch cross-lattice style alloy wheels (Part No. NAM 9073 | 425 kg maximum-load rating | 28 mm offset – marked on wheel, but I also later checked this by measurement & calculation) from a vendor in Braintree, Essex; less than one-hour’s drive from my home on Canvey Island, Essex.

All five of these MG Montego wheels featured the following markings surrounding the flat portion that abuts the car’s wheel-hub:

F 89 H T MAX LOAD 425 KG P. TEST

6Jx15CH28 NAM 9073 DATE/MELT

MADE IN BRITAIN E.I.F. X-Ray

Given that I now have a set of SEVEN MG Maestro 5½J x 15 inch cross-lattice style alloy wheels, the five MG Montego 6J x 15 inch cross-lattice style alloy wheels are probably now surplus to my needs!

Mine would not be the first Triumph to have been fitted with MG Maestro or Montego cross-lattice style alloy wheels, as indicated by the following picture of a Triumph GT6 and the topic-thread post on Wednesday, 29th November 2006 (i.e. 12 years ago).

Triumph GT6 with MG Maestro or Montego 15 inch cross-lattice style wheels



Board index » The Triumph Dolomite Club » The Public Bar - General Chat » What other wheels are there?

viewtopic.php?t=628

« There was a car at this year’s TDCIR with MG Maestro turbo alloys on. »

If seeking to acquire either MG 2000 Maestro or Montego, cross-lattice style, 15 inch alloy wheels, of 5½J x 15 inch or 6J x 15 inch sizes respectively, be aware that there are some very similar looking 1982~90 MG Metro cross-lattice style, 13 inch alloy wheels (with circular, central trim-cap | wheel-offset = 48 mm!?!), of 5½J x 13 inch size, with PCD of 4 x 4 inches (i.e. 101•6 mm) and/or 4 x 100 mm, which are NOT compatible with the MG Maestro or Montego wheel-hubs, yet alone those of the Triumph Toledo or Dolomite!

https://www.wheel-size.com/size/mg/metro/

https://www.wheel-size.com/size/mg/metro/1982/

https://www.wheel-size.com/size/mg/metro/1982/

MG Metro 5½ x 13 inch cross-lattice wheels

[tony g]

Nice write up Nigel ! How much for the unneeded Montego wheels? (if youre selling)

Cheers

Tony

[naskeet]

Nice write up Nigel ! How much for the unneeded Montego wheels? (if youre selling)

Cheers

Tony

Personal message sent

[naskeet]

To get some idea of comparative weight, I weighed both the MG Maestro 5½J x 15 inch and MG Montego 6J x 15 inch cross-lattice style wheels without tyres on my bathroom scales. I expected the wider wheels to be heavier, but the following results suggest otherwise.

MG Maestro 5½J x 15 inch cross-lattice style wheels: weight (on Vanguard bathroom scales) = 1 st 3½ lb (i.e. 7•94 kg)

MG Montego 6J x 15 inch cross-lattice style wheels: weight (on Vanguard bathroom scales) = 1 st 2½ ± ½ lb (i.e. 7•49 kg)

When and if I get the opportunity, I shall reweigh the wheels on my local post office’s parcels weighing scales.

Although the 185/55 R15 tyres on the first set of two MG 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 GKN 5½J x 13 inch wheels, the actual installed tyre section-widths (i.e. distance through the air chamber, between the external inboard & outboard tyre-sidewall surfaces) proved to be noticeably different!

Measuring the section widths of the Firestone S211, 185/70 R13 tyres on the Dolomite Sprint wheels, plus the Michelin MXV2, 185/55 R15 and Cheng Shin Maxxis MA-551, 185/55 R15 tyres 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 also weighed the three wheel & tyre assemblies on my bathroom scales, the results of which were as follows:

Dolomite Sprint GKN 5½J x 13 inch wheels & Firestone S211, 185/70 R13 (? 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

When I further investigated tyre technology, I discovered that the nominal section-widths of tyres, are defined with reference to specific wheel-rim widths (variously referred to as the “standard rim width”, “measuring rim width” or “design rim width”). For the same nominal tyre section-width, the specific wheel-rim widths which are used to define the nominal tyre section-widths, tend to increase with decreasing tyre side-wall aspect ratio.

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

Tire Specs Explained: Rim Width Range

« Because tires have flexible sidewalls, a single tire size will fit on a variety of rim widths. A tire's rim width range identifies the narrowest to the widest rim widths upon which the tire is designed to be mounted during its tens-of-thousands of miles and years of service. »

« The width of the rim will influence the width of the tire. A tire mounted on a narrow rim would be "narrower" than if the same size tire was mounted on a wide rim. »

« Note: Because the overall diameter of a steel-belted radial is essentially determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width. »

« The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10". »


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

Tire Specs Explained: Measuring Rim Width

« The measuring rim width is the industry standardized rim width upon which the tire must be mounted in order to confirm it meets its dimensional targets. Because the width of the rim will influence the width of the tire, a standard rim width for every tire size is assigned and must be used. »

« This standardized measuring rim width allows all of the tires produced around the world to meet the same dimensional standards and therefore, be equivalent with regards to their physical size. The measuring rim width is sometimes referred to as the tire's "design rim width". »

« The assigned measuring rim width changes with the tire size's section width and with the tire size's aspect ratio. As tire section width increases, the measuring rim width increases proportionately in 1/2" increments. Therefore, relatively narrow wheel widths are assigned for smaller tires while wider wheel widths are assigned for larger tires. »

« Additionally, relatively "narrow" measuring wheel widths are assigned for taller profile tires (75-series sizes) which graduate in 1/2" increments to the wider wheel widths assigned for lower profile tires (40-series sizes). »

Range of Wheel Sizes for Given Tyre Sizes

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

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


Range of Tyre Sizes on Given Wheel Sizes

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

NOTE: Although this website might not list tyres of certain section-widths and/or aspect ratios, this does not mean that they are unavailable in all territories, including Great Britain.

Wheel: 14 x 5½ > Tyres: 165 mm min | 175 mm or 185 mm ideal | 195 mm max

This wheel size is used on the MG Montego & Maestro

Wheel: 14 x 5½ > 40 Tyres: min – none listed | ideal – none listed | max 195/40 R14
Wheel: 14 x 5½ > 45Tyres: min – none listed | ideal – none listed | max 195/45 R14
Wheel: 14 x 5½ > 50Tyres: min – none listed | ideal 175/50 or 185/50 R14 | max – none listed
Wheel: 14 x 5½ > 55 Tyres: min 165/55 R14 | ideal 185/55 R14 | max 195/55 R14
Wheel: 14 x 5½ > 60 Tyres: min 165/60 R14 | ideal 175/60 or 185/60 R14 | max 195/60 R14
Wheel: 14 x 5½ > 65 Tyres: min 165/65 R14 | ideal 175/65 or 185/65 R14 | max 195/65 R14
Wheel: 14 x 5½ > 70Tyres: min 165/70 R14 | ideal 175/70 or 185/70 R14 | max 195/70 R14
Wheel: 14 x 5½ > 75Tyres: min – none listed | ideal 175/75 or 185/75 R14 | max 195/75 R14
Wheel: 14 x 5½ > 80 Tyres: min 165/80 R14 | ideal 175/80 or 185/80 R13 | max – none listed

Wheel: 15 x 5½ > Tyres: min – 165 mm | ideal – 175 mm or 185 mm | max – 195 mm

This wheel size is used on the MG Maestro.

Wheel: 15 x 5½ > 45 Tyres: 165/45 R15 min | 185/45 R15 ideal | max 195/45 R15
Wheel: 15 x 5½ > 50 Tyres: 165/50 R15 min | 175/50 R15 ideal | max 195/50 R15
Wheel: 15 x 5½ > 55 Tyres: 165/55 R15 min | 175/55 or 185/55 R15 ideal | max 195/55 R15
Wheel: 15 x 5½ > 60 Tyres: 165/60 R15 min | 175/60 or 185/60 R15 ideal | max 195/60 R15
Wheel: 15 x 5½ > 65 Tyres: 165/65 R15 min | 175/65 or 185/65 R15 ideal | max 195/65 R15
Wheel: 15 x 5½ > 70 Tyres: none listed – min | 175/70 or 185/70 R15 ideal | max 195/70 R15
Wheel: 15 x 5½ > 75 Tyres: none listed – min | 175/75 R15 ideal | max – not listed
Wheel: 15 x 5½ > 80 Tyres: 165/80 R15 min | 185/80 R15 ideal | max 195/80 R15

Wheel: 15 x 6 > Tyres: min – 175 mm | ideal – 185 mm or 195 mm | max – 205 mm

This wheel size is used on the MG Montego, Montego Turbo & Maestro Turbo and the MG F & TF.

Wheel: 15 x 6 > 45 Tyres: 175/45 R15 min | 185/45 or 195/45 R15 ideal | 205/45 R15 max
Wheel: 15 x 6 > 50 Tyres: 175/50 R15 min | 195/50 R15 ideal | 205/50 R15 max
Wheel: 15 x 6 > 55 Tyres: 175/55 R15 min | 185/55 or 195/55 R15 ideal | 205/55 R15 max
Wheel: 15 x 6 > 60 Tyres: 175/60 R15 min | 185/60 or 195/60 R15 ideal | 205/60 R15 max
Wheel: 15 x 6 > 65 Tyres: 175/65 R15 min | 185/65 or 195/65 R15 ideal | 205/65 R15 max
Wheel: 15 x 6 > 70 Tyres: 175/70 R15 min | 185/70 or 195/70 R15 ideal | 205/70 R15 max
Wheel: 15 x 6 > 75 Tyres: 175/75 R15 min | 185/75 or 195/75 R15 ideal | 205/75 R15 max

The two 70-Series tyres of size 185/70 R13 and 185/70 R15, have the same the “standard rim width” of 5 inches, so when both are installed on 5½ inch wide wheel rims, one might expect them to have identical installed section-widths.

Similarly, one might expect two different 185/55 R15 tyres (i.e. different model designation or even from different manufacturers), having the same “standard rim width” of 6 inches, to have identical installed section-widths, when both are installed on 5½ inch wide wheel rims.

However, my own previously mentioned personal observations, have shown this to be untrue, which leads one to question the precision with which “nominal section-widths” are quoted. For example, a tyre of 185 mm “nominal section-width” might actually mean that the section width is within the range 185 ± 4•999 . . . mm (effectively having a tolerance of ± 5 mm); given that available tyre nominal section-widths, increase in increments of 10 mm.

Hence, it is conceivable that two different 185/55 R15 tyres (i.e. different model designation or even from different manufacturers) installed on identical wheels, could have installed section-widths that differ from each other by as much as 10 mm (i.e. 2 x 4•999 . . . mm); leading to differences in wheel-arch to tyre side-wall clearances that differ by as much as 5 mm (i.e. 4•999 . . . mm).

The Reduction in aspect ratio of tyres for 15 inch wheels, from 65% for 185/65 R15 tyres to 55% for 185/55 R15 tyres has associated increases in the “standard rim width” from 5½ inches to 6 inches respectively. Based upon the “industry rule of thumb” outlined above, one might expect the installed tyre section-width of a 185/65 R15 tyre (5½ inch “standard rim-width”) to be about 5 mm wider than that of a 185/55 R15 tyre (6 inch “standard rim-width”), when installed on the same wheel rim width, but other as yet unidentified factors might also influence the outcome.

In addition to possible production variation between individual Triumph Dolomite & Toledo cars, these factors could potentially explain why some owners experience rubbing between the tyres and rear wheel-arches, when the car is equipped with MG-F or MG-TF 6J x 15 inch wheels and 185/55 R15 tyres.

[naskeet]

The previous post on Monday, 10th December 2018, has now been updated to include details of the tyres’ actual installed section widths.

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

Range of Wheel Sizes for Given Tyre Sizes

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

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

Tyres: 185/55 R15 => Wheels: 15 x 5 minimum | 15 x 6 standard | 15 x 6½ maximum

Noting the stated standard wheel-rim widths of 5 inches and 6 inches for 185/70 R13 and 185/55 R15 tyre sizes respectively, one might have predicted the actual installed section widths of these tyres on 5½ inch wide wheels, to have been circa 190 mm and 180 mm respectively:

Triumph Dolomite Sprint 5½J x 13 inch wheel & 185/70 R13 tyre – predicted installed tyre section-width = 190 mm

Triumph Dolomite Sprint 5½J x 13 inch wheel & Firestone S211, 185/70 R13 tyre – Installed tyre section-width = 189¼ ± ¼ mm


MG 2000 Maestro 5½J x 15 inch wheel & 185/55 R15 tyre – predicted installed tyre section-width = 180 mm

MG 2000 Maestro 5½J x 15 inch wheel & Michelin MXV2, 185/55 R15 – Installed tyre section-width = 189¾ ± ¼ mm

MG 2000 Maestro 5½J x 15 inch wheel & Cheng Shin Maxxis MA-551, 185/55 R15 – Installed tyre section-width = 193¼ ± ¼ mm

It appears that the actual installed tyre section-width of both the Michelin MXV2 and Cheng Shin Maxxis MA-551, 185/55 R15 tyres, on 5½J x 15 inch wheels, is about 10~13 mm more than was predicted by the tyre-industry’s rule of thumb!

[naskeet]

There are several reasons why I sought to substitute 15 inch diameter wheels on my Triumph Toledo 1300 “HL Special”, in place of the existing five Triumph Dolomite Sprint 5½J x 13 inch GKN alloy wheels with Firestone S211, 185/70 R13 M+S tyres. Those reasons can be summarised as follows:

1) For reason of circa 10% improvement in fuel economy, I wanted to return the car to its “original” state of overall engine gearing associated with the standard-profile 175 SR13 (i.e. 175/80 R13) tyres, fitted by Mann Egerton on the five 5½ x 13 inch Cosmic alloy wheels, but with a tyre of slightly lower-profile for improved road holding.

2) I wanted to use 65-Series tyres, which for a given rolling-circumference, would give the least rolling resistance and hence greatest fuel economy, as concluded from tyre-industry research conducted during the early-1980s.

3) The car has rested on the Firestone S211, 185/70 R13 M+S tyres since circa mid-1999 which would probably require replacement, before I put the car back on the road.

4) The 185/70 R13 tyres and other tyres for 13 inch diameter wheels are becoming progressively less readily available (i.e. more restricted choice of brands, tread patterns and climatic application – summer, winter or all-weather) and their unit cost is becoming relatively expensive compared to lower-profile tyres for larger-diameter wheels, now commonly fitted to more modern cars; current medium range cars typically being factory-fitted with either 15 or 16 inch diameter wheels.

5) Sourcing enough 15 inch diameter wheels having a 4 x 3¾ inch (i.e. 4 x 95•25 mm) PCD – pitch circle diameter, circa 35 mm wheel-offset and preferably 5½ inch width or alternatively 6 inch width, appropriate to the Triumph Toledo, is likely to become progressively more difficult, and possibly more expensive as time passes.

6) If I need to replace the tyres, then it makes economic sense to replace the wheels at the same time.

Points 1) and 2) could readily be achieved by using a 185/65 R15 tyre on a 15 inch diameter wheel; something I had calculated in the mid-1980s, before these tyre and second-hand wheel sizes became readily available.

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 and the factory-standard 155 SR13 (i.e. 155/80 R13) tyre size are 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

155/80 R13 – 79 T / 83 T XL | 48 results

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

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 a few days ago, I found the following options:

185/65 R15 – 88 T or 88 H / 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=

From the published proceedings, of an engineering research conference about wheels & tyres, held in the early-to-mid 1980s (a document I discovered during circa 1983, in the Cranfield university library, when I was a postgraduate engineering student), I learned that rolling resistance is reduced by maximising tyre external circumference and that for a given external circumference, the optimum tyre aspect ratio is circa 65%; both of which contribute to minimising fuel consumption.

The research project compared several tyres, of nominally identical external rolling-circumference, having aspect ratios of 80%, 70%, 65% and 60%. A graph of rolling resistance versus aspect ratio, was in the form of a back-to-front J-shaped curve. Tyres with an 80% aspect ratio had the greatest rolling resistance, whilst those with either 70% or 60% aspect ratio, had comparatively reduced rolling resistances of similar magnitude, but those of 65% aspect ratio had the lowest rolling resistance of all.

What effect a further reduction in aspect ratio would have on rolling resistance wasn’t explored; probably because few if any ultra-low-profile tyres (i.e. circa 20%~55%) were readily available at that time, for mass-produced, road-going cars. I suspect there has been more recent research pertaining to this, which it would be prudent to check before finalising my choice of tyres and/or final-drive ratio.

Rolling Resistance and Fuel Economy

http://barrystiretech.com/rrandfe.html

Rolling Resistance and Fuel Economy (Continued)

http://barrystiretech.com/rrandfe2.html