Quote:
Originally Posted by mattW
A) Obviously there is some point where tyres burst because of pressure but I'm sure its not anywhere near the sidewall rating or even 10% over...
B) The reason I think race cars need wide tyres is so that the heat is spread over a large area and doesn't affect the properties of the rubber, narrow tires at high psi with normal driving shouldn't get even close to temperatures where the heat negatively affects traction. In fact the higher the pressure the lower the temperature would be because of less deformation.
If you can tell me what is actually behind there being less friction I will believe you, I just haven't seen any decent reason besides 'race cars have wide tires'... Why do race cars have wide tires.
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A) A case of a balloon is a 1 cycle to failure. Tires would not be failing from one loading but from fatigue from multiple loading cycles. Fatigue strength is reduced from both the amplitude of the cycle but also from higher mean values as well. There is your 10% overinflation.
B) No sorry I cant explain why, tires are more complex then people give them credit for. Back to the wide vs narrow, a dragster runs for 5+ seconds, that is not enough time to modify the properties of the rubber so your counter argument does not hold. Drag racers have been lowering tire pressures for traction (how low they go might blow your mind). Sorry I can not do better than "it just is" but "it just is" has held across North American dragstrips for as long as we have had dragstrips.
edit: Best guess as to why lower pressures yield more traction is the tire can better mold itself to the irregular surface of the pavement.