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Old 03-May-2005, 11:23 AM
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Worn tyres

My D208's are down to the wear indicators front and back but becasue i have used them on the track they appear to have kept their profile. Now i wouldnt be happy to use them like that in the wet but for a dry trackday can someone tell me if its a bad thing to use very worn tyres? Does the rubber compound change as you go deeper into the tyre? I would have thought that if most of the rubber has gone then there will be less to move around so you will get better handling, plus more tyre in contact with the road.

Discuss...
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Old 03-May-2005, 11:38 AM
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I'm really not the best person to be replying to this thread but I would have thought that they would be ok in the dry. They would only need to get warm.

I don't know anything about differing compounds as you wear the tyre down but if you've only just reached the wear indicators then I believe the only thing you are starting to lose is their ability to disperse standing water.

Someone who knows what they are talking about will be along in a minute
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Old 03-May-2005, 11:58 AM
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I can see the argument you're putting forward Paul and no doubt it is worth consideration.
The big thing though is that you are unsure, and I think that has answered your question.
You'd be happy thrashing round a track on tyres which still had an obvious amount of wear left in them.
Even if I told you it was safe, would you REALLY be confident in doing the same on tyres at the end of their service life?
And what if the track day is a bit damp?????
Just my thoughts................
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Old 03-May-2005, 12:07 PM
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I see what your saying Andy but to honest they feel fine on the road and i dont worry about them (except in the wet), i'm just wondering if i'm missing something somewhere! WJB in his briefings always says that you should make sure you have loads of tread left. What i dont want to do is put a nice new set on ready for holiday time then wreck them on the track.

I know that in certain car racing series where you have to use road tyres they have scrubbing machines which take new tyres down to 1mm of tread so they still have a pattern but the tread blocks are so small they dont move around much so it must be okay?


At the end of the day all the grooves do is allow the tyre to displace water. A damp track wouldn't matter as long as the tyre was hot would it? Its only in standing water where it might be a problem.

I dont know much about tyre technolgy, racing and trackdays are a learning curve for me!
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Old 03-May-2005, 12:18 PM
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They don't just disperse water via the channels.
The edges of the tread blocks also form part of the design in that they effectively "cut" into the damp coating on the road surface.
When the tyres wear, these edges become blunt & are therefore less effective.
One of the reasons why worn tyres may feel less positive.
The water dispersal argument is less of interest to me ...bear in mind that the formula for aquaplaning is 1mm of tread at 50mph in 1" of water to reach the point at which it will occur.
Bearing in mind how tight my employers are with money..the one thing they won't skimp on is tyres and we consider a tyre to be unfit for patrol at anything below 2.5mm of tread - rain or shine.

[Edited on 3-5-2005 by Rushjob]
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Old 03-May-2005, 12:22 PM
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Quote:
Originally posted by Rushjob
They don't just disperse water via the channels.
The edges of the tread blocks also form part of the design in that they effectively "cut" into the damp coating on the road surface.
When the tyres wear, these edges become blunt & are therefore less effective.
One of the reasons why worn tyres may feel less positive.
The water dispersal argument is less of interest to me ...bear in mind that the formula for aquaplaning is 1mm of tread at 50mph in 1" of water to reach the point at which it will occur.
Bearing in mind how tight my employers are with money..the one thing they won't skimp on is tyres and we consider a tyre to be unfit for patrol at anything below 2.5mm of tread - rain or shine.

[Edited on 3-5-2005 by Rushjob]

That's very interesting, I didn't know that.

Thanks mate
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Old 03-May-2005, 12:30 PM
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Or you could ask yourself why there was a pair of part worn 208's in the skip at Cadwell. Looked as if they had only done a days racing then been lobbed for a new pair. Ragged on the edges and hardly touched in the middle. If they were that good on track when worn, the racers wouldn't change them would they?

Anyway, they'll be on Glyn's ST for TA4, so we'll soon find out.
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Old 03-May-2005, 12:43 PM
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Heat cycles come into it as well though Jools, especially with tyres that are used for racing. Also the profile of the tyre is much more important on a bike than it is with a car tyre.

I read somewhere that the tread design (on bike tyres) is only for asthetics and does very little to aid wet or damp grip, (i think it was an interveiw with someone from Dunlop). Most modern bike tyres are not very good in the wet because the design trys to get as much rubber on the road as possible so fewer grooves. Its the heat and rubber compound used that gets the wet grip

I'm not trying to get a few more road miles out of my set, i just dont want to chuck them away if i can still use them on the (dry) track. I'll get a new set for the road and then swap them for the track or leave them on if its wet or damp.

Good discussion guys!
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Old 03-May-2005, 12:48 PM
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Very interesting, why not give Steve at Wraysbury tyres a call and see what he says.

www.wraysburytyres.co.uk or 01932-562299
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Old 04-May-2005, 09:22 PM
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Quote:
Originally posted by Jools
Or you could ask yourself why there was a pair of part worn 208's in the skip at Cadwell. Looked as if they had only done a days racing then been lobbed for a new pair. Ragged on the edges and hardly touched in the middle. If they were that good on track when worn, the racers wouldn't change them would they?

Anyway, they'll be on Glyn's ST for TA4, so we'll soon find out.


heat cycles, ragged edges, profile
whatever they've got to be better than the macadams
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