Tire Pressures- Road Race
Tire Pressures- Road Race
I only have a year of experience with my then mostly stock Evo. I now have a bigger set up of street tires and I am looking to play with tire pressure, but I have little idea where to start. I have Nitto NT05 265/35-18s. I have not been to the track with this setup, so I do not know how they would run on stock pressures (32F 29R), but will be going this upcoming weekend after being aligned and corner balanced on my coilovers tomorrow. Let me know what you guys run, or would recommend to run! Thanks!
fill it up with nitrogen. 
I usually run for the start 34 - 32 , the front heats up higher anyway after couple of laps. But i never was a real track guy.
Benefit of the nitrogen in the tires, the temperature there for the pressure will be more consistence.
I don't know those tires so i cant really say anything else.
I'm sure the more seasoned track guys have they own tricks what they can share with you
I usually run for the start 34 - 32 , the front heats up higher anyway after couple of laps. But i never was a real track guy. Benefit of the nitrogen in the tires, the temperature there for the pressure will be more consistence.
I don't know those tires so i cant really say anything else.
I'm sure the more seasoned track guys have they own tricks what they can share with you
fill it up with nitrogen. I usually run for the start 34 - 32 , the front heats up higher anyway after couple of laps. But i never was a real track guy.
Benefit of the nitrogen in the tires, the temperature there for the pressure will be more consistence.
I don't know those tires so i cant really say anything else.
I'm sure the more seasoned track guys have they own tricks what they can share with you
I usually run for the start 34 - 32 , the front heats up higher anyway after couple of laps. But i never was a real track guy. Benefit of the nitrogen in the tires, the temperature there for the pressure will be more consistence.
I don't know those tires so i cant really say anything else.
I'm sure the more seasoned track guys have they own tricks what they can share with you
I know what you are saying but I have a compressor (regular air!) and thats what I will be using.
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Joined: Feb 2008
Posts: 254
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From: SoCal
I'd aim for 36-40 psi hot, all 4 tires ... fronts will heat up more quickly (since they are responsible for both steering and traction vs. just traction for the rears), as will the outside tires since more weight will be on them during cornering.
So, if running clockwise, you could start with the following cold pressures at the beginning of the day:
LF 30 32 RF
LR 34 36 RR
Then equalize all 4 tires to the same pressure after the first session.
From there, adjust in 2 psi increments:
- to correct understeer: raise the front, or lower the rear
- to correct oversteer: lower the front, or raise the rear
So, if running clockwise, you could start with the following cold pressures at the beginning of the day:
LF 30 32 RF
LR 34 36 RR
Then equalize all 4 tires to the same pressure after the first session.
From there, adjust in 2 psi increments:
- to correct understeer: raise the front, or lower the rear
- to correct oversteer: lower the front, or raise the rear
I'd aim for 36-40 psi hot, all 4 tires ... fronts will heat up more quickly (since they are responsible for both steering and traction vs. just traction for the rears), as will the outside tires since more weight will be on them during cornering.
So, if running clockwise, you could start with the following cold pressures at the beginning of the day:
LF 30 32 RF
LR 34 36 RR
Then equalize all 4 tires to the same pressure after the first session.
From there, adjust in 2 psi increments:
- to correct understeer: raise the front, or lower the rear
- to correct oversteer: lower the front, or raise the rear
So, if running clockwise, you could start with the following cold pressures at the beginning of the day:
LF 30 32 RF
LR 34 36 RR
Then equalize all 4 tires to the same pressure after the first session.
From there, adjust in 2 psi increments:
- to correct understeer: raise the front, or lower the rear
- to correct oversteer: lower the front, or raise the rear
Also, my assumption with tire pressures is that lower pressure will grip better but heat and wear faster. First, is this the right idea? And if it is, why run higher than stock tire pressures?
EDIT: for your understeer/ oversteer corrections, aren't they actually opposite of that? Again, this is operating off the assumption that lowering tire pressure increases grip.
Last edited by Protostar1; Jun 2, 2009 at 06:03 AM.
Yes, corner balancing equals the weight at all four corners...play w/ tire pressures has always been a front and rear thing for the most part. I guess if u have a predominantly left hand turn course, u may make adjustments left and right, but probably not at my skill level.
Playing with the pressures, especially the rear always the rear end of the car to rotate more or less to your liking...just quick and dirty way of making adjustments rather than messing with a rear sway bar trackside (for example).
If u add too much rear PSI than the rear will lose too much grip and rotate too much...it's all an adjustment within a certain traction range to get the feeling u like.
(least this is how this newb understands it.
)
Playing with the pressures, especially the rear always the rear end of the car to rotate more or less to your liking...just quick and dirty way of making adjustments rather than messing with a rear sway bar trackside (for example).
If u add too much rear PSI than the rear will lose too much grip and rotate too much...it's all an adjustment within a certain traction range to get the feeling u like.
(least this is how this newb understands it.
)
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Yes, corner balancing equals the weight at all four corners...play w/ tire pressures has always been a front and rear thing for the most part. I guess if u have a predominantly left hand turn course, u may make adjustments left and right, but probably not at my skill level.
Playing with the pressures, especially the rear always the rear end of the car to rotate more or less to your liking...just quick and dirty way of making adjustments rather than messing with a rear sway bar trackside (for example).
If u add too much rear PSI than the rear will lose too much grip and rotate too much...it's all an adjustment within a certain traction range to get the feeling u like.
(least this is how this newb understands it.)
Playing with the pressures, especially the rear always the rear end of the car to rotate more or less to your liking...just quick and dirty way of making adjustments rather than messing with a rear sway bar trackside (for example).
If u add too much rear PSI than the rear will lose too much grip and rotate too much...it's all an adjustment within a certain traction range to get the feeling u like.
(least this is how this newb understands it.
)
A lot of it will depend on the surface as well. Slick surface = less psi/softer suspension setup, grippier surface more PSI/harder suspension.
I typically have the newer guys here in Dallas start out at 38-40PSI (all around) for street tires and work from there. Too slick, we let air out. Rolling over? We add more (we have one surface here that you can get 45+psi on street tires to try and avoid rollover).
For the NT-05, I've seen recommendations ranging from 34-35psi HOT to "whatever you want".
When I autocrossed on my NT-05's (to break them in
), on asphalt I ran 33F/35R psi (hot) and it felt really good. On concrete I ran 40F/42R (hot).
ETA: one guy at our track event in May had been running like 29 or 30PSI (that's what the Audi guys at the track recommended
) and his front tires were DEAD after just a couple track days/1000 miles. He'd rolled them over WAY over the sidewall. He went out on the track owners OK with 38-40PSI in the front and was able to do a couple more sessions without really losing any speed, but a LOT less damage to the tires.
I typically have the newer guys here in Dallas start out at 38-40PSI (all around) for street tires and work from there. Too slick, we let air out. Rolling over? We add more (we have one surface here that you can get 45+psi on street tires to try and avoid rollover).
For the NT-05, I've seen recommendations ranging from 34-35psi HOT to "whatever you want".
When I autocrossed on my NT-05's (to break them in
), on asphalt I ran 33F/35R psi (hot) and it felt really good. On concrete I ran 40F/42R (hot).ETA: one guy at our track event in May had been running like 29 or 30PSI (that's what the Audi guys at the track recommended
) and his front tires were DEAD after just a couple track days/1000 miles. He'd rolled them over WAY over the sidewall. He went out on the track owners OK with 38-40PSI in the front and was able to do a couple more sessions without really losing any speed, but a LOT less damage to the tires.
A lot of it will depend on the surface as well. Slick surface = less psi/softer suspension setup, grippier surface more PSI/harder suspension.
I typically have the newer guys here in Dallas start out at 38-40PSI (all around) for street tires and work from there. Too slick, we let air out. Rolling over? We add more (we have one surface here that you can get 45+psi on street tires to try and avoid rollover).
For the NT-05, I've seen recommendations ranging from 34-35psi HOT to "whatever you want".
When I autocrossed on my NT-05's (to break them in), on asphalt I ran 33F/35R psi (hot) and it felt really good. On concrete I ran 40F/42R (hot).
ETA: one guy at our track event in May had been running like 29 or 30PSI (that's what the Audi guys at the track recommended) and his front tires were DEAD after just a couple track days/1000 miles. He'd rolled them over WAY over the sidewall. He went out on the track owners OK with 38-40PSI in the front and was able to do a couple more sessions without really losing any speed, but a LOT less damage to the tires.
I typically have the newer guys here in Dallas start out at 38-40PSI (all around) for street tires and work from there. Too slick, we let air out. Rolling over? We add more (we have one surface here that you can get 45+psi on street tires to try and avoid rollover).
For the NT-05, I've seen recommendations ranging from 34-35psi HOT to "whatever you want".
When I autocrossed on my NT-05's (to break them in
), on asphalt I ran 33F/35R psi (hot) and it felt really good. On concrete I ran 40F/42R (hot).ETA: one guy at our track event in May had been running like 29 or 30PSI (that's what the Audi guys at the track recommended
) and his front tires were DEAD after just a couple track days/1000 miles. He'd rolled them over WAY over the sidewall. He went out on the track owners OK with 38-40PSI in the front and was able to do a couple more sessions without really losing any speed, but a LOT less damage to the tires.
more pressure in the rear helps induce oversteer/help the car rotate. That will depend also on your suspension and alignment too. Find something that works for you
Some drivers I know run 10# differentials F/R to help with alleviating understeer.
Some drivers I know run 10# differentials F/R to help with alleviating understeer.
Might be an off topic stupid question but what tire pressure gauge are you track junkies using? I'm looking for a highly accurate digital gauge for both my road tracking and drag racing set ups. Please advise with links.
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