I'm cross-posting this thread here and in the Wheels and Tires forum since I think the information should be seen by a wider audience:

Here's a link to a very informative web page on the effects of tire pressure on hydroplaning resistance. Since the OEM Bridgestone SO2 tire has a bad reputation for hydroplaning sensitivity, I thought this would be relevent information for our group.

In brief, even modestly lower tire pressures (25 psi in a tire designed to be used at 35 psi) can significantly reduce hydroplaning resistance. I suspect that as our tire wears, and it loses water-evacuation capabilities, maintenance of correct tire pressure becomes even more important.

 

Glad you brought this up, I was just worrying the other day about this. It was a torrential downpour and I was driving, nearly hydroplaning at 45-50 MPH. Thanks!

-Chase

 

Great information. Thanks!

 

If my memory serves me, I was taught in USAF pilot training that a tire hydroplanes at nine times the square root of the tire pressure when water depth exceeds tread depth. A tire inflated to 36 psi will, therefore, hydroplane at 54 mph when the water is deeper than the tread. At "owners manual" pressure of 32 psi, our S2000s should hydroplane at just under 51 mph when water depth exceeds tread depth. How does this compare with your experiences? Can anyone confirm that my info is correct?

 

Your information is correct ... in general. However, all is not equal - aviation and automobile tire designs are different since they have different performance parameters. For example, cornering grip while taxiing is certainly not an important consideration for the tires on aircraft, whereas abrasion and heat resistance are. Furthermore, the cross section of aviation tires is rounded compared to the more rectangular cross section of automobile tires. Plus, some automotive tread designs are more efficient at displacing water than others, and new breakthroughs in rubber compounds (like Bridgestone's UNI - T AQ) allow increased wet grip compared to other compounds.

I can report that relatively new OEM tires (near 7mm or 8/32" tread depth) do not hydroplane at 60 MPH, even when there is a thick film of standing water on the road (raindrops are clearly seen making individual splashes on the roadway), and well worn SO2s are planted and stable in a straight line at just over 50 MPH under similar conditions. These conditions are frequently encountered down here in the subtropics. I have heard from 2 other owners that their cars hydroplaned at 75 and 80 MPH respectively on tires of unknown tread depth. I once induced an out of control spin in my car at 55 MPH on an autocross course when I hit a deep puddle in the rain while cornering.