Visit The Dirt Forum for More Information

Author Topic:   AR IMCA Tire Pressure ?
chickenlittle
Dirt Full Roller

Total posts: 63
posted July 20, 2005 08:59 PM  
Has anyone experimented with high tire pressures with the IMCA tire? By high I mean around 20-25lbs. I run on a hard, dryslick track most of the time. Was wondering if it might stiffen the sidewalls some and give more side bite. I know they always say lower the pressure to 8-10 lbs for dry track, but wanted to try something differnent. Just wanted to get some opinions on the issue.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted July 20, 2005 09:43 PM  
This may sound kinda silly, but I've been going to do a test with air pressures by testing the amount of G's the tire would hold at different pressures to find the optimum range. I haven't gotten around to it yet. I do know that when you drop pressure in a given tire it DECREASES that corners weight.....I never really thought about that before and when I first bought my scales I was playing around seeing what adjustments did what and I noticed that. It really surprised me, but now that I think about it, when you drop pressure it lowers that corner of the car therefore reducing the corners weight.

old racer
Dirt Maniac

Total posts: 112
posted July 21, 2005 07:23 AM  
There are some gains to be made with higher air pressures on IMCA tires. If you watch most cars the RR is running on the sidewall on corner exit which causes the tire contact patch to not bite the track. After testing on black slick for a day, we saw the best for our car was 14 to 18 lbs of air. You must remember the tire acts as a spring so you may need other adjustments to suspension to make the higher pressures work. It will make the car much more consistant and you will be using the tire as it was designed to be used. Use nitrogen instead of air for best results.
Good Luck

Kromulous
Dirt Forum Champ
Total posts: 796
posted July 21, 2005 07:27 AM  
Done the same thing on the UMP Hoosier tire, most people think i am insane running 18 to 20lbs in the RR & RF put i do quite often.

The car, and the tire seem to respond well to it and the wear is 2 to 1 better.

Usually i got people looking at the sidewalls of the tires and tell me if there rolling under alot. Then adjust from there.

juliaferrell
Dirt Freak

Total posts: 370
posted July 21, 2005 07:50 AM  
be surprised how many people are junking setups due to WAY too low air pressure. Has anyone ever called Hoosier or McCreary to get ball park pressures? Well I have......and it sure at 6, 8, 10, or 12 pound of air.........What do you want the car to run on the rim?

jws
Dirt Maniac

Total posts: 115
posted July 21, 2005 08:31 AM  
Definitely have to keep that RR from rolling under. If you feel like you are under sprung or under shocked on the RR or if the car gets a mysterious push in the middle of the corner, you might be rolling it under. It usually takes 14 to 15 pounds on a fast heavy track to cure this on my car.

Kromulous
Dirt Forum Champ
Total posts: 796
posted July 21, 2005 09:04 AM  
You can usually feel the car when the air pressures are to low, our car will feel kinda wishy washy, and has that pushy feeling.

chickenlittle
Dirt Full Roller

Total posts: 63
posted July 21, 2005 09:07 AM  
Thanks for the info. You have confirmed what I was thinking. I figured the tires are designed to be used with more air pres than what most people are using. didn't make much sense to have it rolling over on teh sidewall. Got to be tough on the tire too. Would cause it to heat up pretty fast too.

Back to the Archives