Hoosier's , Tire Pressures & Track Temps

[RalphieViper]

Hoosier\'s , Tire Pressures & Track Temps

I'm trying my luck at Limerock next month and need some advise. What are the rules for tire pressures? More or less psi depending on how cold it is? Different type of track? Any info is greatly appreciated!!!!

Ralph

 

[FrankBarba]

Re: Hoosier\'s , Tire Pressures & Track Temps

Hoosier has a web site. You should be able to get all the 411 that you need. Do you have any Track experience in your Viper? IF you do not, Tire pressures are the least of your worries.

 

[Russ Oasis]

Re: Hoosier\'s , Tire Pressures & Track Temps

Ralph,
With no flame intended, even if you have no track experience, tire pressure is VERY important. If you don't have track experience, start with the pressures that Hoosier recommends. Keep checking your pressures after each session and keep them at the recommended level.

 

[Frank Parise]

Re: Hoosier\'s , Tire Pressures & Track Temps

Ralphie, a good starting point on the street-legal Hoosier road race tire is 40 PSI hot. Try going out with cold pressures of about 32 front and 30 rear. When you return to the pits, adjust your tire pressures up or down so that you have 40 all around.

 

[JGarrett]

Re: Hoosier\'s , Tire Pressures & Track Temps

After finding a starting cold pressure; a pyrometer is really the only way to go. Coming in after some hot laps will tell you a huge amount from how your suspension is working to how much to adjust your pressures. Hot pressure readings are far too unreliable to be of use. You need the temp of the tire across it's width to know what's going on. Think about it is it the high temp on the outside or the middle that is affecting the air pressure or is the temp high all across the tire that is affecting it. The pressure is simply a result of many factors and you can't tell which.
Cheers,
Jim

98 GTS

 

[pdmracing]

Re: Hoosier\'s , Tire Pressures & Track Temps

be careful, lime rock is very bumpy & when cold it will take you lots of laps to get up to temp. I like 42 psi hot

 

[Frank Parise]

Re: Hoosier\'s , Tire Pressures & Track Temps

Hot air pressures too unreliable to be of use? That's the first time I ever heard that one. The pyrometer is a very useful tool for determining whether you have the optimum wheel alignment, particularly camber and, to a lesser degree, toe. It will also tell you if you have way too much or way too little air pressure. But, this Hoosier has a very wide sweet spot to operate within. The tire is designed to operate with an optimal shaped footprint that is acquired by adjusting to the optimal air pressure for the track conditions on any particular day. There is a balance that has to be struck between ultimate performance and ultimate wear. In an endurance race, say of 2-3 hours or more, you will likely be running pressures in the high 40's if you want the tire to last. For a single qualifying lap, you may like the mid to high 30's. For a typical 20-30 minute run session, you'll probably be somewhere in the 38-42 range. Unless you want to realign your car at the track, make ride height changes, shock adjustments, etc., hot air pressures are the most commonly used tool to tune the car to the handling preferences of the driver. Hope this helps rather than confuses the issue.