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 Post subject: Tyre help
PostPosted: Tue Sep 11, 2012 2:17 pm 
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Location: Winscombe, North Somerset, England
On my last two outings to Castle Combe I have had a tyre do this...

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and on Saturday this also happened...

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...steel strands protruding through the tyre.


It happened on the same wheel, Left/Front. Castle Combe is a clockwise circuit so most of the corners are right handers.

Can anyone enlighten me? Is it the tyre, camber?

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 Post subject: Re: Tyre help
PostPosted: Tue Sep 11, 2012 3:50 pm 
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Martin

Thats negative camber if its wearing on the side edge of a tyre - how many shims have you between the subframe & mounting bracket.

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 Post subject: Re: Tyre help
PostPosted: Tue Sep 11, 2012 8:23 pm 
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Maybe tire pressure too low :?:

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 Post subject: Re: Tyre help
PostPosted: Tue Sep 11, 2012 8:35 pm 
It's hardly going to be the amount of neg that does it unless the tracking's out.

My daily runs 2 degrees 30 minutes of negative camber (+/- 10 minutes) on the rear wheels by design and although I have had enough fun with it to have killed a pair of expensive back tyres in 18,000 miles and 14 months since new, at least they were evenly killed! :oops:

I think that tyres just aren't what they used to be. :wary:


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 Post subject: Re: Tyre help
PostPosted: Tue Sep 11, 2012 11:18 pm 
I'm going to say too much neg camber too (causing overheating). If the tyre pressure was too low it would've been the outside of the tyre to suffer because the force of body roll would stretch the tyre inwards on right handers and put the load on the outer edge. I don't know what pressures you use but I would say anything near 30psi would be ideal. Too much toe-out could also cause this but it's unlikely because it should affect both fronts? Worth getting it checked though.
I don't know if it makes a difference but I noticed that the steering column seemed hideously voilent when you were cornering hard, it seemed to jump about slightly. :shock: Maybe this points towards too much force going through the rack because of alignment issues?
Also remember that you were using kerbs heavily and they could've ripped the tyre. The kerbs wouldn't cause the bulging or overheating but maybe they did cause the steel strands to protrude? I think they're made of sharpish concrete at Combe and you were using them hard..


Last edited by Dolly-Nut on Thu Sep 13, 2012 12:11 am, edited 1 time in total.

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 Post subject: Re: Tyre help
PostPosted: Wed Sep 12, 2012 11:17 am 
I wouldnt think it was neg camber problem. May be the tyre Pressure being too high and the tracking out. That's where I would look. Don't forget as the tyres get hotter the pressure goes up. Softer compound tyres means more heat and therefore more pressure.


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 Post subject: Re: Tyre help
PostPosted: Wed Sep 12, 2012 11:29 pm 
Tracking. insufficient camber would war the tyre 1/3 of the way acress from the outer.


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 Post subject: Re: Tyre help
PostPosted: Thu Sep 13, 2012 12:11 am 
Actually looking at the pictures there doesn't seem to be that much negative camber so my vote now goes towards tracking/too much toe-out.


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 Post subject: Re: Tyre help
PostPosted: Thu Sep 13, 2012 7:02 pm 
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Quote:
Actually looking at the pictures there doesn't seem to be that much negative camber so my vote now goes towards tracking/too much toe-out.
I'm with you Dan!

Steve

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 Post subject: Re: Tyre help
PostPosted: Thu Sep 13, 2012 7:16 pm 
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Given that it's 'smeared' a bit, it's toe out. Camber tends to just wear un-evenly (in my experience..)

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 Post subject: Re: Tyre help
PostPosted: Thu Sep 13, 2012 7:32 pm 
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Thanks for the replies. The tyres are inflated to 30 psi and always are when I start out. I'll get them checked over tomorrow to see what's what.

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 Post subject: Re: Tyre help
PostPosted: Fri Sep 14, 2012 12:00 am 
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I would say too much toe out.
Rebecca uses 26 psi which rises to 31 when hot so perhaps this might help too.
She uses Toyo 88's which seem damn fine tyres.

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 Post subject: Re: Tyre help
PostPosted: Fri Sep 14, 2012 4:25 pm 
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Too much pressure would wear the centre of the tyre more than the edges though?
Does it understeer at all? I ask as I seem to remember you have very stiff front springs...

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 Post subject: Re: Tyre help
PostPosted: Fri Sep 14, 2012 5:24 pm 
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It does understeer a bit.

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 Post subject: Re: Tyre help
PostPosted: Fri Sep 14, 2012 8:20 pm 
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I've forgotten where I was going with that, possibly something about the spring rate being too stiff and not working the tyres fully, I obviously ignored the picture posted that shows it leaning on the full tyre, though that is only one corner of course... But it's probably a toe issue, though after such a recent re-build, you probably checked it didn't you?

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It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark, and we're wearing sunglasses.
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