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.
My question is why are you recommended to increase the psi of the front tires
to reduce understeer? If higher pressures reduce grip then increasing pressure would make it worse...
Here is a quote from a
tire info place about overinflation:
"An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi,
they could be damaged more easily when encountering potholes or debris in the road, as well as experience irregular tread wear. Higher inflated tires cannot isolate road irregularities as well causing the vehicle to ride harsher and transmit more noise into its interior. However, higher inflation pressures reduce rolling resistance slightly and
typically provide a slight improvement in steering response and cornering stability. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures."
Other than the threat of pothole damage (offset by longer following distance and more attention on the road for hypermilers) its seems overinflation could actually be safer than normal levels, albeit more uncomfortable...