Quote:
Originally Posted by NHRABill
Sorry, I have to disagree the MAX pressure of a tire is not the safest pressure it is called max for a reason. Yes I understand the logic and results of over inflating the tire for daily commuting use I do it myself, but a fully loaded car or truck with overinflated tires or tires set to the Max is dangerous. This is an obvious observation by most anyone with an ounce of common sense.
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And the reason is what? The tire is designed to function at load with that much weight, so the shear resistance of the rubber can take it, ergo lighter loads will not stress it as much. Perhaps if your car's dampers are not maintained, the higher pressure can highlight worn shocks, but tire pressure is not the issue.
Quote:
Originally Posted by NHRABill
The reason I mentioned the Mfr. pressure as a safe starting point and not that of the tire is because the car is designed to be safe at those conditions. If you removed your stock tires and rims from your car increased the size or changed the height of your sidewalls then the mfr. recommendations goes out the window and can only be used as a guideline.
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The manufacturer recommended that pressure to minimize road noise and keep a nice ride, a higher pressure does not make the tire less safe. You build more heat at lower pressures, and that is what causes tire failure.
Quote:
Originally Posted by NHRABill
if you are into racing then you understand that all tires have different compounds i wouldn't put the Hoosier quicktimes on my truck to tow my car to the racetrack the same as I wouldn't run a set of McCreary's on my wifes Cadillac. The tires compound, diameter, height, width environmental conditions and vehicle you put them on varies so much that there is NO universal Max pressure. I run 10PSI in my truck tires when running on the beach of NC outer banks I need to drop my motorcycle pressure down to 25 to get better traction when it is a 90 degree hot day and I am cursing the back roads of Princeton, NJ along the river having a good time. i used to run 10psi in my supercomp dragster on a average night where I would run 14 psi in my ultra quick 8 vette under the same conditions. When I was commuting I would run Max psi in the daily driver and no more after I tore the tread off of the tire while driving at a high rate of speed spinning me out at 70mph on the Garden state parkway in southbound summer congestion.
The point is know your car and there is no right answer take all factors into consideration for your ride.
I can't imagine worrying about rolling a sidewall when racing. a 40 or even 50 series tire on a scca course would shred on a high HP and heavy weighted car before it rolled even if set to 10 psi.
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Exactly. Different tires have different geometries and different compounds, making the car manufacturers' recommendations useless. What I meant to say with my track car is tire pressure must be higher to keep from scrubbing the shoulders to maintain the contact patch. You get better grip by maintaining the tire shape with higher pressure. Same concept, just don't exceed the sidewall maximum.
And I have drag raced as well; lower pressure gets better grip but you better not run at highway speeds or you will overheat them. And don't corner with them aired down either.