Quote:
Originally Posted by JimD
I don't think we are in complete disagrement but I also think your pressures are low for track use for many tire/cars/drivers. Here is an article recommending 38-45psi:
http://www.motoiq.com/MagazineArticl...-Pressure.aspx
I also think we all agree it varies by car, driver, and tire (and I agree the tires in the pictures above seem to be properly inflated). But increased pressure will deal with the exact issue that OP had. It decreases understeer, decreases driving on the shoulder of the tire and decreases temperature minimizing the potential for chunking. If you google something like "tire pressure for racing" you will find several articles, all recommending increased pressure for racing. The Tire Rack article recommends up to 50 psi for Hoosers. There was also a good article about using tire temperature as the way to judge correct tire pressure. I got the idea of using white compound on the thread to shoulder juncture out of the Roundel. It isn't the best method but is better than just blindly guessing or assuming normal inflation levels are correct.
The only real point I am trying to make is that the evidence of tire damage is consistent with running too low a pressure on the track. With higher pressures, I think the results would be different but I haven't tried it yet to know for sure. That is why I asked if anybody had damage at higher pressure. Even better would be for somebody to test different tire pressure to see what it takes to keep the tread (and not the shoulder) on the track when racing. I will probably run 40 or maybe 42 cold with these tires my next autocross. I won't get more than one or two tries to adjust pressure so it won't be a great test but I am confident I will have better results than if I ran 32psi. I'm running a square setup with stock suspension and may or may not run the fronts 2-4psi above the rears. If I was still staggered, I think I would definitely increase the fronts a little. That seems to be the recommendation from those with more experience than I have. |
I don't think you understand my point I'm trying to make, is that you're running too much pressure regardless of what tire.
Increasing pressure for racing is to save their butts for when someone doesn't properly monitor their tires, and ends up destroying them.
No Hoosier tire will ever run 50 PSI, period.
There is NO way you can conclude that low pressure is to blame. You can argue that he ran too much pressure, and the tire wasn't gripping, was skipping across the ground (which it will with too much pressure) causing the chunking to happen.
Running such high pressure is limiting the tire to do what it wants, which is load up. When you prevent it from doing so, it will not like it, and you'll chew the tires in an unfavorable way.
Here are my tires running at "low" pressures, if you want to call that. I can update this with another picture as my tires are now past the wear bars if you really want, but you can see that with a proper tire...you will not see chunking of any kind. 30 PSI HOT fronts in autocross, and 38 HOT on the track.
My tires are monitored with chalk for rollover. I'm past the arrows, but the tires like the low pressures and grip, so I run them as such.
In addition, I'll leave you with this, the new BFG Rivals. They LOVE low pressures, you wanna know why?
Let me introduce you to Sam Strano. Multi-Champion SCCA National driver. This is on his FRS, in the rain. These pressures are actually increased due to the rain.
Are you going to tell a National Multi-Champion he is wrong with his pressures because the door sticker and Tirerack said 40 PSI? I thought not...