what is ideal tire pressure for the direzza z1 star specs? i got beat in my class (stu) today by an m3 and i was sliding all over the place. it was a VERY tight course where i had to downshift to 1st a couple times, but i still should have been faster. this was my second time on these tires at autocross, also at the same time i put the tires on i put on jic flta-2 coilovers. i'm running -2.5 camber in the front and -1.25 camber in the rear with zero toe front and rear and the springs are different than the stock flta-2s, it's 8kf/9kr i believe. i need any advantage i can get as soon as possible (there is another event tomorrow). today i was running 32psi all around after one run, but when i won my class previously i was at 35psi all around cold. i have no clue about tire pressure, but i had a big diff today and i see all the competitive people watching their tire pressure like a hawk, so i assume it's important. any info is greatly appreciated.

 

I find 44 rear 42 front hot works for me. This is with both r compound and stock tires. M3's are bad *** with a good drivers and setup, nothing to be ashamed of losing to one.

 

chalk your tires... they will tell you if they need more or less air.

That said, if you are sliding all around, how are you sliding? Under or oversteer?

If you are understeering, then I bet you were driving like me -- forcing the issue and not being smooth.

If oversteering, then you need to let some air out. You might also change the ACD to be more FWD (to gravel or snow). This will help you pull out of turns a bit.

Different surfaces and temperatures will call for different tire pressures.

 

i have no acd. = (
and it was a combo of of over and under. on really tight corners i was understeering (brake induced mostly), but on sweepers and high speed the rear was coming out. i've really been trying to eliminate understeer cause it's harder to deal with on a course. when i checked the indicators on the tires the very tips of the triangles were wearing, so i thought it was good, but i've been told that the direzzas should be at about 35psi (hot/cold/always). there was a good layer of dust on the lot today that i don't think got fully cleared out by the event as i wasn't the only one sliding around, even the vettes on v710s and a6s were all over the place, but the tires seemed really greasy. i saw everyone constantly monitoring tire pressure, and a couple people wetting their tires trying to cool them off, to try to maximize grip. is this even worth it? or should i be looking at leveraging my suspension for more grip?

 

Stop guessing. Get 1 learn how to use it.

 

fireman thats really high pressures... i guess its individual, but most guys (near me) run 35psi hot..

any higher and the R-comps become to slippery.

 

yeah i use 30-35 also

 

that's what keeps the temps across the tread the same for me auto-X or track use. I thought it was temp not pressure that gets the tires greasy. Anything lower and I roll the tires onto the sidewalls.

 

I am using Toyo RA1 with -3 camber front and -1.1 rear, 0 toe front and rear. Robispec kW 3 set by him. Robispec adviced me to use 40psi front and 42 Rear for our 2mile course (hot). He told me that if the car pushed to much ( understeer ) I should increase the rear to 44psi. and if it oversteared I should go to 40 psi. I tried this setting and I was beating everyone at the track, it worked great. I hope this helps.

 

Robi who? What does he know?


I'm running a bit more camber rear and a bit less camber front with MR Bilsteins and Espelir springs + several other suspension mods same tires and close to the same pressures and hell yes it works.

 

It's a little late now :0) but I'll try and help a bit for next time.

If you are understeering in the tights and oversteering in the sweepers, then you need to let air out of the rears and slow the hell down in the tights. The understeer in the tights is likely caused by too much entry speed, bad line and/or trail braking. Trust me, because that's how I drive and the outside of my front tires is completely flat from it. When I have a slower entry speed and can actually drive the car through a tight corner, rather than fighting it, I end up 1-2 seconds faster on a ~41 second course.

Between runs, check your tire pressure and if you're a big geek, get a pyrometer and check the temperature. Yesterday, on my 3rd run (which is on video), I said "I need to let air out of my tires." The car was getting loose because the tires had heated up and the air pressure was up. I neglected to let air out and on my 4th run I was sideways twice and got a DNF because of it. I let air out (about 10# all around) and laid down what would have been my fastest run except I tapped a cone.

I forgot my water sprayer, so I couldn't cool my tires (it really helped when it was 105* out, but it was only about 90* yesterday).

 

I'm assuming this was sarcasm? It's hard to hear it when reading on the net

 

not that hard

 

I am usually around 33-34psi in the front and 37-39psi in the rear.

Air pressure I have found really depends on your camber setup.

 

And the tire you use
And the temps of the surface you run them on
And when you check them (cold), hot (just ran) (a few minutes after you ran)