Minimum psi with slicks? Fwd.

[v8s_are_slow]

Just wondering how you go about determining the best psi for your slicks. I know ya don't wanna have too much air in them but what's the minimum? I'm seeing some folks running 7.0 up to around 12-13 or so. I've been running 13 psi but wondering how much lower I can go. I start worrying about wearing out the sidewalls. And one run at 13 psi when I start out is enough to heat the tires up a couple of degrees, and then I start breaking traction. And since I'm about to have more power, I need all the traction I can get.

 

[silver bullit]

Well do you have slicks, and when you over spin your tire in the burn out box you can over heat them and make the traction crap.

Also try different launch rpms, and clutch release
Test and experimenting is the only way.

 

[v8s_are_slow]

Yes, I have slicks. My traction has been crappy from not getting them hot enough but dunno how I could get them "overheated". Street tires yes, but slicks?

 

[silver bullit]

LSD? and suspension you got good motor mounts?

 

[v8s_are_slow]

Stock tranny, have the mounts. I know the tranny needs the LSD but for purposes of the thread, I'm just wondering about the slicks. And how low is too low? And how would you know if it's too low other than popping the tire off the wheel. Lol.

 

[silver bullit]

To many variables car and track, you can check to see what the lowest the manufacture recommends and you can experiment with different pressures to suit your setup, style, + track conditions and track temps
Trail and error is what it is about.

Specs on car and what is you 1/4 time sheet?

What kind of suspension mods you got?

 

[h8r]

You wont wear out the side wall, because the tire expands when it gets up to speed the force of the car accelerating makes the weight transfer to the back, in turn it makes the front end lift. So, you are taking weight off the car... If it is too low the MPH should decrease, and the tire may spin on the wheel. I would go with 14 psi.

 

[silver bullit]

You wont wear out the side wall, because the tire expands when it gets up to speed the force of the car accelerating makes the weight transfer to the back, in turn it makes the front end lift. So, you are taking weight off the car... If it is too low the MPH should decrease, and the tire may spin on the wheel. I would go with 14 psi.

Yes and no, if you take off 100 lbs on the front instead of the rear you screw the weight balance, on a front drive drag car you want all the weight close or centered on the front axles, as it is front drive the front will wanna lift with weight transfer.

I would stiffen the rear end shocks or suspension up to take the play of this weight transfer out.

Obviously you need to search and find some topics covering front drive launch and race techniques.

So, you are taking weight off the car... If it is too low the MPH should decrease, and the tire may spin on the wheel.

If a heavy front drive car was key you would see 3000-4000lb front drive cars more often, but thats why they weigh under 2500 lb or less. As stated above weight distribution/balance.

I would not take it lower than 10 you may get away with 8 buy you need to try it on yourself.

 

[v8s_are_slow]

You wont wear out the side wall, because the tire expands when it gets up to speed the force of the car accelerating makes the weight transfer to the back, in turn it makes the front end lift. So, you are taking weight off the car... If it is too low the MPH should decrease, and the tire may spin on the wheel. I would go with 14 psi.

Well, I'm not worried about wearing out the tire at wot down the track. I'm worried about the really low psi and driving it back around going really slow and all that weight of the car on the tires. That's the part I'm worried about.

 

[h8r]

Yes and no, if you take off 100 lbs on the front instead of the rear you screw the weight balance, on a front drive drag car you want all the weight close or centered on the front axles, as it is front drive the front will wanna lift with weight transfer.

I would stiffen the rear end shocks or suspension up to take the play of this weight transfer out.

Obviously you need to search and find some topics covering front drive launch and race techniques.



If a heavy front drive car was key you would see 3000-4000lb front drive cars more often, but thats why they weigh under 2500 lb or less. As stated above weight distribution/balance.

I would not take it lower than 10 you may get away with 8 buy you need to try it on yourself.

I never said you want the car to be heavy. My point was that momentum will make the car squat in the rear from the acceleration( This reduces the amount of force driving the front of the car down.. I was talking about the tires not getting worn on the sidewall). So, we are saying the same thing in a round about way.... Something needs to happen in the rear to keep the front planted better, as you said stiffness of the rear suspension would def. help.

 

[h8r]

When I said if it's "to low the the MPH will decrease".... I was talking about the tire pressure... Not the weight of the car. I think you misunderstood me. Sounds like you need to refrain on saying I need to research how a front drag car works....

 

[crab1092]

Well i have 26x10 mickey thompson slicks and put between 8 and 9.25psi depending on the track and what not . They have over 100 passes on them and show no sidewall wear. I would not worry about wearing them out. Just dont do u turn at 40 mph and you should be fine.

 

[v8s_are_slow]

Well i have 26x10 mickey thompson slicks and put between 8 and 9.25psi depending on the track and what not . They have over 100 passes on them and show no sidewall wear. I would not worry about wearing them out. Just dont do u turn at 40 mph and you should be fine.

I really wish you had pictures of how the tire looks at this psi at a standstill. At 13psi, I have a very slight wrinkle. I've done passes at around 10 psi (when I've let the air out to get it back down to 13psi and then when it cooled back down, the pressure went low) and when I take the right hand turn at the end of the track, the steering wheel wants to stay pointed in that direction for some odd reason. What would you notice or what ill effects would you have on slicks if the pressure was too low?

 

[kiggly]

The car will feel bobbly and bouncy at the top end if the pressure is too low. In 26x10 goodyears, I ran as low as 4.5psi. Those tires liked to work in the 5-6psi range. The 28x10 MT's like to work in the 7-8psi range. The shorter the sidewall is, the more pressure it needs. The 28x10 MT's are just starting to wrinkle while sitting still at 8psi. Drop the pressure until your traction doesn't get any better, then go back up just a pinch.

Kevin

 

[crab1092]

One difference in my setup and most others is i run tubes in my tires. At 9psi i have very little wrinkle. At 8 psi its wrinkly but nothing like i have seen some other cars run at the track. To me the worse part of low air pressure is at the end of the run when i let off the gas. My car floats a little and at those speeds it really wakes you up. But while i am on the gas it goes straight and really doesnt feel funny. You are right about taking turns. IT feels like it wont turn and the steering wheel will not self correct.

What slicks do you have exactly? It would be a whole lot easier to give you advice if i knew what you had. But in general the smaller the slick the more air pressure you should run.

 

[daren_p]

Think in general you want to lower the pressure if your having traction issues but this in turn can hurt handleing at the top end of the track & it will also increase rolling resistance, slowing you down. You have to find that happy medium. Make sure your getting enough heat into them, according to what the manufacturer recommends & have heard people say it takes a few passes before they start to hook to their full potential.

 

[bmwisthekey]

how are your burnouts, u putting u some good smoke? 2nd gear burnouts?

 

[v8s_are_slow]

My burnouts have been pretty decent. Slicks are M&H's. Guess that's the name of them. Size is 8.5/23.0/15's.

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[crab1092]

Arent you getting a T-67? IF so i would look into a set of bigger slicks. I can break 26x10 loose with my 20g at a little unde 400whp. So if you going to pushing that big of a turbo i dont think 8.5/23 slicks are going to be able to really do your car justice.

 

[v8s_are_slow]

Yeah, I already have the turbo. Just waiting on a few parts to come in so I can hopefully get my car back up and running in a couple of weeks. I guess I'll see how things go when it's on and go from there.

 

[slowgsr]

Ive ran my slicks as low as 6psi w/tubes. these were MT's.

 

[desolateboosted]

My burnouts have been pretty decent. Slicks are M&H's. Guess that's the name of them. Size is 8.5/23.0/15's.

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Ah, you're barely heating those guys up. I'd stay in it for 1-3 more seconds.

 

[v8s_are_slow]

Yeah, car keeps pulling me forward though even though I'm not trying to move. Lol. You can see my rear tires are locked up. Makes it kinda difficult to keep burnin em but maybe I could keep spinning if I shift to 2nd. Sure I need to but the one time I tried that, the tranny didn't really wanna shift and I burned the hell outta the clutch and it smelled for the rest of the day. New clutch going in, with T-67. Hopefully running tomorrow night.

Oh yeah, and in that run, I pulled a 1.760 60ft.

 

[spoolints04]

Don't ever try to shift while doing a burn out! Thats a sure way to kill a tranny. Start your burnout in second gear. Also alot of people don't know to spin the slicks alittle bit in the water box to get them wet all the way around.

 

[ortorc]

if your running down to 8 psi or less i suggest that you get them screwed to the wheels. as far as tires are, you should have plenty of tire to handle 400 hp how is your suspension set up? if it'sa complete drag car, get the hardest rear srings you can with a hard shock. this will keep the rear end from squatting and keep more weight on the front. when I was dragging my chevy cavalier i used a z24 rear spring with a lowering sring in the front to keep the front end planted because the z24 rear was about 1.5 inches taller than the lowering and also was alot stiffer spring rate to keep the front end down and the rear end from squatting the rear to the ground.