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Best Tire Air Pressure


Being trained in the aviation industry, I always use the maximum specified pressure for the car, as placarded on doorjamb, glove box, etc.
We were taught that hydroplaning speed (in knots) is nine times the square root of the tire pressure. (MPH would be knots times 1.15)

More pressure in tires would be safer- to a point. Too much, and you lessen contact area and wear out middle of tread faster.

I bet it’s from a Corvair, the difference was needed to control the handling.

Or you could just use 10 times the square root of MPH. It’s good to see the derivation, though.

So I should beware going over 59-63 mph in the rain with my tires at 35-40 (cold vs hot) psi.