Tirerack tread depth article

[ryoder]

Tirerack put out an article about tread depth and safety in wet conditions. I really believe them on this one. I don't let my wife's or my car ever get below 4/32. I did a 360 at 70mph one time in my Camaro due to low tread depth on a just rained on highway. I wasn't braking or turning when the spin occurred either. http://www.tirerack.com/tires/tests/...y.jsp?ttid=85&

[Luke@tirerack]

thanks for noticing

[ctgene]

Interesting article, thanks for the post...I had a car hydroplane on me once and did the 360 thing and luckily no one was near me except the guard rail which saved me from who knows what...

[EHS]

Originally Posted by ryoder

Tirerack put out an article about tread depth and safety in wet conditions.
I really believe them on this one. I don't let my wife's or my car ever get below 4/32.
I did a 360 at 70mph one time in my Camaro due to low tread depth on a just rained on highway. I wasn't braking or turning when the spin occurred either.

http://www.tirerack.com/tires/tests/...y.jsp?ttid=85&

While tread depth and design has some influence in hydroplaning, the critical factor is not tread depth, but the speed at which you are driving in the rain (as you found out).

NASA (among others) has done a wealth of research, and it doesn't matter how deep your tread is, if you are driving to fast. Anything more than 57 mph in your Corvette, and you are asking for trouble.

Here's why:

http://howthingswork.virginia.edu/page1.php?QNum=1342

"...a NASA study showing that there is a minimum speed at which a tire will begin to hydroplane and that that speed depends on the square root of the tire pressure. Higher tire pressure tends to expel the water layer and prevent hydroplaning, while lower tire pressure allows the water layer to remain in place when the vehicle is traveling fast enough.. a large truck tire is typically inflated to 100 PSI and resists hydroplaning at speed of up to about 100 mph. But a passenger car tire has a much lower pressure of about 32 PSI and can hydroplane at speeds somewhat under 60 mph. That's why you have to be careful driving on waterlogged pavement at highway speeds and why highway builders carefully slope their surfaces to shed rain water quickly."

Two more links, one with a table to make the math easier:

http://oea.larc.nasa.gov/PAIS/Groove.html

and

http://www.mountainflying.com/hydroplane.htm

[ryoder]

That sucks.
Looks like I'll be running my runflats at 100psi from now on.

[UstaB-GS549]

Originally Posted by ryoder

That sucks.
Looks like I'll be running my runflats at 100psi from now on.

I'm going to run my race tires at 1,000 psi in the rain.

[Wolfmanjohn]

Good advice there. My son learned about all the above plus positraction and throttle in the rain after spinning one-and-a-half in his Camaro. Fortunately, it stopped at the "lesson learned" stage.