Lower tire pressure at the track. Does it work?

[propellerhead]

Yet another newb question...

I remember lowering the tire pressure back when I was into 4WD. It helped the big 33" tires almost wrap itself around rocks and crap on the trail. I hear about people lowering their tire pressure at the drag strip. Does it really help? Wouldn't it just cause the center section to raise up?

[Da Prez]

yes it does, too much air and you will spin your ass off...i always run my slicks at 12psi...

[Paul's_03SVT]

I am a newb also but last time at the track my buddy with drag radials lowered his pressure and it didnt help at all. We went down a little at a time and it got progressively worse (60's). I think on street tires its not worth it at all and stock air pressure is the best.

[Futurama]

you have to just play with different pressures, whether you are using full slicks or just street tires.

most street tires like 18-20psi

drag radials 15-18 psi

slicks even lower.

but you really just have to make a pass, write down your 60ft, change your pressure, and see if it helps or hurts it. every car launches different.

[GR8WHITE]

Depends on the combo, but I've always had better luck with lower tire pressures.-to a point. I usually start a little higher and lower the pressure until the tires hook hard. I think the highest pressure you can run without spinning is the key. My car tends to "float" with too low tire pressure, usually at around 10.5 psi..My car likes 11 psi, but every car is different. Experiment until you find the right pressure....

[RainsStang]

You always run as much air in your tires as you can without spinning the tires. The more air you have in the tires the more stable the car will be.

[mikeb]

Every car is different. Mine likes higher pressures in the slicks; I run @ 15psi. You just have to experiment with tire pressure, burnout technique, and launch technique to find the best combination.

[spankustang]

I run my drag radials at 14-15psi and used to run my slicks at 10-12

[propellerhead]

I can understand how underinflating the tire can lead to a larger footprint and more flex so it doesn't break traction so easily. But I guess it only works up to a certain point. I'm not that consistent yet to be able to tell if deflating the tires made a difference or not. My times still vary by up to 0.2 secs in a single track visit.

Ok, what about Nitto 555s? Not the drag radials. What PSI would you guys recommend?

[unbeatable]

duh like everybody should know that.

[GR8WHITE]

Ok, what about Nitto 555s? Not the drag radials. What PSI would you guys recommend?


Keep them at 35 PSI and avoid the track!

[ceyko]

Ok, what about Nitto 555s? Not the drag radials. What PSI would you guys recommend?

Why don't we start at 24 tomorrow and work down 2 at a time? I'm curious about this now.

[Sergio]

Keep them at 35 PSI and avoid the track!

:cool:

[Futurama]

I can understand how underinflating the tire can lead to a larger footprint and more flex so it doesn't break traction so easily. But I guess it only works up to a certain point. I'm not that consistent yet to be able to tell if deflating the tires made a difference or not. My times still vary by up to 0.2 secs in a single track visit.

Ok, what about Nitto 555s? Not the drag radials. What PSI would you guys recommend?
no one can tell you that.

listen mr enginneer! go out and do some testing. it will be different on every car, even 2 mustangs with the same mods.

[turbostang]

The most optimum pressure/temperature is going to be different with every car. Lower pressures will work to some extent. The idea is to get the biggest footprint on the ground. Once you decrease the pressure past the "sweet" spot the tire will cup and the middle of the tire will not even touch the ground - It's hard to tell on the track and some cars even perform better at the track with the tires like this. Usually they are the lower h.p. cars though. If you look at a few launch pictures of cars with slicks you can see the differences in tire pressure. A slick give an exaggerated view of what a street radial does - but it is much easier to see.

OTOH - a higher pressure will cause the center of the tire to bulge and only ride on the center of the tire.. which can reduce the part of the tire that is in contact with the ground. Same problem brought on by different pressures and a different part of the tire touching the ground. They both make the same end result - less of the tire is touching the ground in the end.

On a car like yours I'd find it hard to believe that it would benifit from anything lower than 25 psi or so. After all the street radials aren't designed to be ran at "lower" pressures....especially short sidewall tires.

[ceyko]

Nice response, and your logic does make sense. I think in our cases (GT owners that are basically stock) we just need a little extra assistance to stop some of the spinning. Likely, you are right. We'll probably notice an increase in performance upto a certain point. I personally won't drop below 20...little worried the bead may break and then I'll be up poop creak...unless Kennedale has a tire service shop on the track that I did not see. :)

Take care,

The most optimum pressure/temperature is going to be different with every car. Lower pressures will work to some extent. The idea is to get the biggest footprint on the ground. Once you decrease the pressure past the "sweet" spot the tire will cup and the middle of the tire will not even touch the ground - It's hard to tell on the track and some cars even perform better at the track with the tires like this. Usually they are the lower h.p. cars though. If you look at a few launch pictures of cars with slicks you can see the differences in tire pressure. A slick give an exaggerated view of what a street radial does - but it is much easier to see.

OTOH - a higher pressure will cause the center of the tire to bulge and only ride on the center of the tire.. which can reduce the part of the tire that is in contact with the ground. Same problem brought on by different pressures and a different part of the tire touching the ground. They both make the same end result - less of the tire is touching the ground in the end.

On a car like yours I'd find it hard to believe that it would benifit from anything lower than 25 psi or so. After all the street radials aren't designed to be ran at "lower" pressures....especially short sidewall tires.

[propellerhead]

I guess I could drop one wheel down to 25 psi and leave the other one at 32 then have someone stand behind my car at launch tell me which wheel spun more...

Hmmm.... Hey slo95.0, still wanna know which octane pollutes more?

[Magnimike1]

I guess I could drop one wheel down to 25 psi and leave the other one at 32 then have someone stand behind my car at launch tell me which wheel spun more...

Hmmm.... Hey slo95.0, still wanna know which octane pollutes more?


That wouldn't be safe, dummy! :D

[32VfromHell]

I guess I could drop one wheel down to 25 psi and leave the other one at 32 then have someone stand behind my car at launch tell me which wheel spun more...

Hmmm.... Hey slo95.0, still wanna know which octane pollutes more?


that is very unsafe. Stick to just gradually lowering it each run to find the sweet spot.

[STRONGNUFF]

I run 17lbs on 315 Nitto DR's, and 45 lbs up front for less rolling resistance.

[propellerhead]

I think I'll try 25 in the rear with my Nitto 555s and 40 in the front with my stock Goodyears. Hearing what you guys run with on what type of tire helps me narrow down a range I want to try. Thanks!

[Maverick]

I think I'll try 25 in the rear with my Nitto 555s and 40 in the front with my stock Goodyears. Hearing what you guys run with on what type of tire helps me narrow down a range I want to try. Thanks!

Prop, totally different for each car...I have same tire you do (only narrower) and run 28psi (seems to work pretty good)...a little spin, but my car doesn't have traction control (like yours), so you should be able to make them "bite"...

Or, you could just drive the house on your way to the track next time and pick me up...I'll crew for ya! (and operate video camera - best way to "reference" launch, i.e. fine tune the car and driver)

Warning - you might end up with a racecar if you hang around me too long! LMAO!

[momo stallion]

dont go balls out off the line with street tires and you dont have to worry about it.