Foximus

iTrader: (13)

So, I was running Hoosier R6's. Im not on BFGoodrich GForce R1's.

Is 36 front, 31 rear a decent ballpark to start with for tire pressures? I havent quite found what makes the car comfortable, and theres only one other cobalt that runs out here, and he's in his own league, way ahead of me, haha.

alredline04

For autocross I would say 36 front is too low. I have been autocrossing for 6 years in he ion or cobalt on street tires or rcomps. It depends on how agressive your front end alignment is. If to are running the stock alignment you will need 46 psi or more in the front to keep off the edge of the tires. You can get away with a few psi lower on less grippy surfaces. The higher camber should allow you to get away with a lower psi. My expeience between the A6 and the V710 ar that they don't like to get very hot. The A6 likes to be watered down right away. The V710 take a few runs. The A6 awards smooth driving with awesome grip and good wear.

The R6 is a road race compound and requires time to get to temp. I've never used them, but I would think you could get away with a slightly lower psi and work them up. I usually like to start where I want to be and let air out as they heat up.

The rears are probably ok. They don't see much work on a fwd. We have 2 events on brand new A6's and the rears still show the mold lines.

scottherbert

I agree with his thinking. For the fronts: 45-50 psi. For the rears: 30-35 psi. As a start point. I have run 50 psi in the fronts before I made camber changes.

Scott

Foximus

iTrader: (13)

i have -1 degree camber, I plan to goto -2. I was at 46 front / 41 rears (any more than 5-6 pound split and the back end wants to loop) and i was still on the sidewalls of my fronts. This was on the Geforce RA1

scottherbert

Just to put this in context, Hoosier 'recommends' -6 degrees of camber. I run about -3-4 degrees for autocross (granted, I have camber plates). I even have -1.55 degrees of negative in the rear.

Scott

alredline04

What are you running for suspension?

I run 43F 33R with the 245 Kumho's on the Saturn. -2.8 camber up front. Rolls right to the edge of the mold line.

I run the pedder's coilovers on the Saturn. It does handle better than the spring, shock, swaybar setup I had before. I actually removed the rear Powell bar and it made the rear more planted, but it still brakes loose easily. No amount tire pressure or damper adjustment fixes it. I think the rear spring rates are just too high.

I went from a car that pushed bad and was trying everything to get it too oversteer. Now I am at the other extreme and trying get the car not to oversteer so easily.

Now driving a stock cobalt turbo that feels perfectly balanced has me thinking I have waisted my time all these years trying improve my driving with my wallet and car parts lol

Spank

Tire pressure is dependent on many factors as mentioned. A6's need more since they have very little sidewall. The mroe camber you have, the wider the wheel in relationship to the tire will allow you to run less.

I have seen 255's run on stock rims, but must run super high pressure. I have seen 285's run on stock RX8 rims and work.

Use a pyrometer. Look at your wear and see how it is doing. Then determine do you need more or less pressure based on the car and your driving.

To get a good idea of pressures we must know as much as possible. When in doubt, pump up hoosiers and save your sidewalls.

Slowbalt

autoxr

I'm on Star specs 255/35/18 with a 8.5 wheel. Pedders, -1.9 front stock rear and XXX bar. I have found any where from 44-47 front and 36-40 rear seems to work. I found on a tighter course I would run 46-47 f and 36r and the car would rotate well. If I upped the rear to 40 I had a little more understeer. My alignment will be hopefully -2.25 tomorrow so we will see how that changes things.

Foximus

iTrader: (13)

See. Its interesting. Im getting a good wear pattern at 45-42 for pressures, but everyone says its "too high" however, as soon as i lower pressures into the thirties up front: the nose slides and massive understeer.

Im on bfg geforce r1's 205/45/15
Fe5 suspension
Eibach springs
Rack spacers, moog endlinks
All prothane bushings
1" rear and 23mm front bar

Wangspeed

iTrader: (2)

It's because you're losing camber mid turn. -1 isn't anywhere near enough with soft springs. We have a macpherson setup and even on pedders my front control arms are almost parallel to the ground. As soon as they are less than 90* from the strut, you're losing camber. I run -2.0 as a compromise between street and track events. Ideally I'd have more, but too much makes it harder to put down power. Damn FWD.

The prothane bushings may be torn by now too. Especially the trailing one. If you're allowed to run metal, there's john's setup. If not, you'd better change them often. This will also help prevent dynamic camber loss.

montecarloman

I've only run one event so I'm not qualified but I noticed my front tires rolling over some as well. I'm also not on slicks but figured I'd share anyway. I'm running 38psi ft with -1.0 degree camber and 40 psi rear with -.5 degrees. I need to bring shoe polish to mark the sidewalls to see really how bad it is.

The rest:

• P215/45ZR17 Contiental Extremcontact DWS
• SS/SC lower front control arms
• Powell Race Shop front lower trailing control arm bushings
• SS/SC Front swaybar conversion
• Moog SS/SC swaybar end-links
• SS/SC rear trailing arm
• Powell Raceshop Hardcore rear swaybar
• SS/TC front struts and rear shocks
• Eibach Pro-kit coil springs

PenguinPIE

iTrader: (5)

I always run 40+ psi in the front and 1 or 2 psi higher in the rear for autox events. I find that anything less in the front will get really close to the tire wall. I'm on 225/40/18 Michelin Pilot Super Sport and stock suspension + Powell hardcore rear sway bar.

stangetr

just for some insight i am road racing and looking to get 32 front and 40-45 hot in the rear to help get the car to rotate, i'm running 235/45 17 r1

Wangspeed

iTrader: (2)

What tires are you running? I'm on 235/40-18 NT01, and the sidewall was waaaay too soft for anything under 38 hot up front. Like rolling onto the lettering soft.

Mark Aubele

He said R1s. I have no idea how he can get away with 32 psi hot up front. I was at 38 on A6s with -2.8* camber, stock suspension, just to stay off the sidewalls.

Wangspeed

iTrader: (2)

Whoops. I totally missed that, thanks. I haven't tried an R1 since the old Tennesee factory closed in the late 90s. The new one is a foreign beast to me. The old R1 had super stiff sidewalls. Guess the new one is similar, at the cost of weight. I'm still quite surprised. Probably more to the puzzle than we know right now.

Foximus

iTrader: (13)

Im planning to goto -2 camber. and i am looking at a set of delrin control arm mounts once money allows. the Prothane have not come apart yet tho.