Trackdays - Tyre Wear
30 January 2001, 12:40 AM
#32
running 50PSI is going to give you less grip, period. It will mean the center of the tyre is doing all the work. It will make it slide more, which could add to the grin factor, it will also do less damage to the side tread blocks.
I think its too high to be honest, i much prefer 38psi, sommat like that, on an Impreza. (my westie runs 20PSI hot, but we wont confuse matters
)
You get far more degredation in the tyre if it is new. This is because the tread block is taller and flexes more, generating excesive heat in the tread, in severe cases this will chunk the tread, normally it leads to the tread block wearing at an acute angle so the inner edge of the block is as it were, but the outer edge is down to the carcass.
Best compromise is to buy some part worn tyres, with say 2mm of tread left on them, these wont suffer from overheating of the tread block and will last much longer than new tyres. Run them around 38PSI hot. Thats the best i have found so far with an Impreza.
I think its too high to be honest, i much prefer 38psi, sommat like that, on an Impreza. (my westie runs 20PSI hot, but we wont confuse matters
)You get far more degredation in the tyre if it is new. This is because the tread block is taller and flexes more, generating excesive heat in the tread, in severe cases this will chunk the tread, normally it leads to the tread block wearing at an acute angle so the inner edge of the block is as it were, but the outer edge is down to the carcass.
Best compromise is to buy some part worn tyres, with say 2mm of tread left on them, these wont suffer from overheating of the tread block and will last much longer than new tyres. Run them around 38PSI hot. Thats the best i have found so far with an Impreza.
30 January 2001, 09:16 AM
#34
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I tried it at Goodwood on Saturday
Had 45 in all 4 before I started (cold) and once they were warmed up this went to 48/49. - I had no pump on me.
This was on part worn cheapies (Capitol I think).
It was very scary, I had next to no grip and nearly came of round (I think it's called) St Mary's in lap 2 and 3 - despite slowing down to about 45Mph (I'm guessing that from the gear / engine revs).
(1st lap was done slow to make sure the tyres were warm).
Reduced the pressures to 37 all round and it was much better. St Mary's was taken at 60-80 (not accurate but you get the idea) from then on.
OK, I'm not ruling it out however. The track was damp whilst I was running with high pressures. I need to actually remember to take my pump next time and try it in the dry.
Ps I got almost no tyre wear !! I reckon these part worns will last me 3 or 4 track days - much better than 1 day with SO2's, they still grip fine in the dry (I would say better as they don't seem to overheat) - you need to warm them up more though.
Had 45 in all 4 before I started (cold) and once they were warmed up this went to 48/49. - I had no pump on me.
This was on part worn cheapies (Capitol I think).
It was very scary, I had next to no grip and nearly came of round (I think it's called) St Mary's in lap 2 and 3 - despite slowing down to about 45Mph (I'm guessing that from the gear / engine revs).
(1st lap was done slow to make sure the tyres were warm).
Reduced the pressures to 37 all round and it was much better. St Mary's was taken at 60-80 (not accurate but you get the idea) from then on.
OK, I'm not ruling it out however. The track was damp whilst I was running with high pressures. I need to actually remember to take my pump next time and try it in the dry.
Ps I got almost no tyre wear !! I reckon these part worns will last me 3 or 4 track days - much better than 1 day with SO2's, they still grip fine in the dry (I would say better as they don't seem to overheat) - you need to warm them up more though.
30 January 2001, 10:00 AM
#35
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Do you think that the 50psi thing is supposed to work only on fresh "decent" rubber? If so that may be why it didnt work for you.
Im gonna give it a go. The moral is to take a foot pump and decent pressure gauge!
James
Im gonna give it a go. The moral is to take a foot pump and decent pressure gauge!
James
30 January 2001, 01:37 PM
#39
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I agree with what Don Palmer has to say re: the buffing of tyres. If you have buffed or shaved tyres heat can dissipate quicker from the tyre and also last 3 to 4 times longer. We proved this when racing in formula ford, buffed tyres also knocked off about 1.25 seconds a lap. Tyre buffing costs very little per tyre. I think Demon Tweeks charge about £10 per tyre and in my book that's an overall saving when particpating in track days.
Also agree completely with John Felstead 50psi seems a bit too high, should be high 30's and check with an accurate guage when the tyre is hot.
BTW John I wouldn't mind a ride in your westie when you're next at Donnington.
Also agree completely with John Felstead 50psi seems a bit too high, should be high 30's and check with an accurate guage when the tyre is hot.
BTW John I wouldn't mind a ride in your westie when you're next at Donnington.
30 January 2001, 02:18 PM
#40
I hadnt thought about that puff, may be worth a straw poll or something to see if that is the case?
You're all welcome for a run in my car, demand outstrips supply of time though so you'll just have to join the queue.
You're all welcome for a run in my car, demand outstrips supply of time though so you'll just have to join the queue.
30 January 2001, 08:02 PM
#41
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Posted from the wheels section as we seem to be going the same way, BTW I have tried part worns and also high pressures with the same results.
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Does anyone know what I can do about tyre wear on airfield days. I tend to use the Subaru on airfields as its great to slide about in 4 wheel drifts, certainly not the fastest way but certainly the most fun in a non competitive way.
However unless its completely sodden this results in extreme tyre wear. I use spare 16 inch rims - the tyres don't have to be road legal, just able to take serious sideways abuse without going to canvas in 2 sessions.
Has anyone any experience in using gravel/tarmac stage tyres in this senario - would they last longer? How pricey and where can I get them from, is it possible to get part worns.
I use slicks on my Caterham and suspect they would fall apart sliding the subaru - has anyone any experience of this?
So far I have tried part worn A520s and SO2s as they were at hand, both succumbed quickly the softer SO2s being the worst.
Any sensible suggestions
Ta in advance
--------------------------------------------------------------------------------
Does anyone know what I can do about tyre wear on airfield days. I tend to use the Subaru on airfields as its great to slide about in 4 wheel drifts, certainly not the fastest way but certainly the most fun in a non competitive way.
However unless its completely sodden this results in extreme tyre wear. I use spare 16 inch rims - the tyres don't have to be road legal, just able to take serious sideways abuse without going to canvas in 2 sessions.
Has anyone any experience in using gravel/tarmac stage tyres in this senario - would they last longer? How pricey and where can I get them from, is it possible to get part worns.
I use slicks on my Caterham and suspect they would fall apart sliding the subaru - has anyone any experience of this?
So far I have tried part worn A520s and SO2s as they were at hand, both succumbed quickly the softer SO2s being the worst.
Any sensible suggestions
Ta in advance
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