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Author Topic:   Air Pressures
downhill
Dirt Roller

Total posts: 5
posted July 20, 2005 08:41 PM  
I have a 3400# car that I am running on a 1/4 mile high bank track. The track usually ends up dry slick and VERY rough. The class we are runnung in is basically hobby stock with a few variations. The biggest difference is our tire rule. We run American Racer 70/205-15SW with no bead locks allowed. I was wondering if anyone can give me some ballpark pressures. Currently I am running RF30 LF26 RR26 LR22. From some of the past messages Ive read I am wondering if these pressures are too high

wetwolfone
Dirt Full Roller

Total posts: 51
posted July 21, 2005 07:08 AM  
quote:
Originally posted by downhill:
I have a 3400# car that I am running on a 1/4 mile high bank track. The track usually ends up dry slick and VERY rough. The class we are runnung in is basically hobby stock with a few variations. The biggest difference is our tire rule. We run American Racer 70/205-15SW with no bead locks allowed. I was wondering if anyone can give me some ballpark pressures. Currently I am running RF30 LF26 RR26 LR22. From some of the past messages Ive read I am wondering if these pressures are too high


They sound a little high except for the left rear. Maybe try:

RF 26
LF 24
RR 23
LR 22

Keep good notes and pay attention to what the car is doing on track (spinning,sliding,etc.)Also right after you finish race, check pressures and see how much each tire is pumping up.

I'm by no means an expert, but I run a similar track with street radials. Hope this helps.



Flanndad
Dirt Freak

Total posts: 255
posted July 21, 2005 08:57 AM  
Search some old post, most people on here will tell you American Racer perform best under 20lbs

14lbs LF RF 18lbs
11lbs LR RR 14lbs

And then I drop them 1 or 2 lbs each for a slick smooth track.

Get one of those laser temp gauges, besides scales it's one of the best investment's you have in trying to understand your car.
It will tell you if you need a caster/camber change, spring change, air pressure change.
Learn how to read tire temp's and you will be suprised at how much better you can get it.

Dixon
Dirt Maniac

Total posts: 153
posted July 21, 2005 03:28 PM  
No offense Flanndad, but I've never been able to get a rf tire to stay on the rim at anything less than 20 psi without a bead-lock, but our track is usually very tacky, so it might work on dry-slick. I'd just be real careful.

downhill
Dirt Roller

Total posts: 5
posted July 21, 2005 05:23 PM  
Thanks for the info, I'll give it a try this weekend

Magic82
Dirt Full Roller

Total posts: 34
posted July 22, 2005 06:05 AM  
On the 3/8 mile medium banked track where I run I set my air pressures at 8-10psi for the left side and 12-14psi for the right side. Our tires are 29-11-15 American Racers on 10" wide rims without bead locks, however, we do run tubes. Our car is 3000 pounds. Some guys even go as low as 6psi on the left front. www.southbuxtonraceway.com

Blind Barney
Dirt Maniac

Total posts: 120
posted July 28, 2005 03:35 PM  
47 RF
42 LF
16 LR
27 RR

J3
Dirt Maniac

Total posts: 188
posted July 28, 2005 03:44 PM  
quote:
Originally posted by Blind Barney:
47 RF
42 LF
16 LR
27 RR

Why so high on the front?

downhill
Dirt Roller

Total posts: 5
posted July 28, 2005 03:53 PM  
Thanks for the tip Blind Barney (lol), see ya saturday.

Blind Barney
Dirt Maniac

Total posts: 120
posted July 28, 2005 05:49 PM  
nevermind J3. Just do it downhill.

Blind Barney
Dirt Maniac

Total posts: 120
posted July 29, 2005 12:17 PM  
On a serious note. I would stick around the high 20's and low 30's. With our track being so rough and not being allowed beadlocks and with your car so heavy you risk popping a bead if you try something in the low 20's.

downhill
Dirt Roller

Total posts: 5
posted July 29, 2005 01:46 PM  
Hey Blind Barney, what do you think about tubes, would that help or am I just creating more work for my self. In the second heat last week I ran 18 in the RR and the car was the best it has been until the tire came off.

Blind Barney
Dirt Maniac

Total posts: 120
posted July 29, 2005 02:41 PM  
I have seen where guys use tubes and the tire spins on the rim. I just saw a mod that had the tube valve half pulled through the rim hole and barely sticking out to put air in it. On a drive tire I would not do it but I think a bead lock would fix that. The only place I would try a tube if I had to is on the LF. Not a fan of tubes but maybe there is some tricks a dirt rookie like myself does not know.

Tire Killer
Dirt Full Roller

Total posts: 47
posted July 30, 2005 12:16 AM  
If you can't run bead locks then I have two words for ya "extream bead" your rims! It's a little tougher to get the tire on, but you won't roll them off near as easy either. I always had better luck with them. Just a thought.

downhill
Dirt Roller

Total posts: 5
posted July 30, 2005 12:36 AM  
Extreme bead? Im not sure what that is. I have heard of guys using a mig welder and putting a couple beads on the inside to create a deeper groove for the tire to sit in, is that the same thing?

sc1 racing
Dirt Freak

Total posts: 419
posted July 30, 2005 08:36 AM  
i think www.mrt-wheels.com has the extreme bead rim. it is designed to replace beadlocks, and for those who can not run bead locks..

racer17j
Dirt Forum Champ
Total posts: 5390
posted July 30, 2005 09:52 AM  
quote:
Originally posted by racer17j:
if you do it right tubes are the way to go use a but load of baby powder and water based lube to mount tire as little as possible water based lubes will evaporate oil based ones wont. i won't run without tubes and haven't had a flat tire in 4 years 18# on the rr

Whats the point in the baby powder and the water based lube?

bobaluuu
Dirt Freak

Total posts: 474
posted July 31, 2005 09:27 AM  
well, when mixed properly they make a perfummy sticky glob that has a rather tangy taste but works well to help tear offs adhere to your visor. some folks say they have to raise their visors slightly to get proper vision but their cost in tearoffs has gone down significantly.

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