Quote:
Originally Posted by slowmover
Where's the evidence that overinflation is beneficial? In forty years of reading about cars (and nearly that in owning them) I've yet to come across that benefit quantified.
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Shoot. I know I've seen some A/B/A testing around here somewhere, but a quick look failed to turn up the thread. I know I have also seen quite a number of posts (more than a dozen) where people noted longer glide distances (in some cases, instrumented) after inflating their tires to sidewall maximum.
In my own case, I have tested three different tires on one of my cars for best cornering grip with different tire pressures. Acceleration and braking were not important to me when I did those tests, but in all cases I found that the best grip was achieved with pressures higher than the placard pressures. (This is for hard-compound true street tires, not R-compound tires nor the not-quite-R compound "street tire class" tires that are now popular in some circles.)
Every tire will have a pressure range where it grips the best. In every case that I know of (for passenger car tires), this pressure range is above the placard pressure that the vehicle manufacturer recommends. It is often not the same as the max sidewall pressure, but the max pressure has always (for me so far!) given better cornering grip than the placard pressures.
For those in the "I won't give up any grip because it's a safety margin" camp: You already have. If you're not running racing slicks, you've already given up grip. You have compromised the grip for minor concerns like being legal to use on the street, actually having some grip in the cold or wet, having some puncture resistance, and so on. So the question becomes: Which set of compromises do you pick?
-soD