Chevy SS Forum banner
1 - 16 of 16 Posts

· Registered
Joined
·
206 Posts
Discussion Starter · #1 ·
I sort of looked through the threads here (but not all) and saw nothing about tire pressure recommendations. I'm going to a "low key" autocross on Saturday (details below) to get a little practice in, seeing how it runs in different modes and just to get my "sea-legs" back.

I started autocrossing in the early '80s with a Triumph TR8. Later years had me in a couple of Escort GTs and then the '95 Impala SS (set up with a Camaro/Trans Am front swaybar and a 400% stiffer Herb Adams rear swaybar, among other things). It's been a number of years since I've done it (except for a national Impala event or two) and can't wait to try out the SS even though I'm not going to be able to do it very often.

In the interest of saving time at the track, I wondered what pressures you have found to work best.

Suggestions?

Thanks,

Tim

Pitt Race Lowkey Autocross ? VDA

Here's some video of the last time I autocrossed. Unfortunately it doesn't show the final run that gave me a third place finish (behind some "expensively" well set up cars and more regular drivers).
 

· Premium Member
Joined
·
7,510 Posts
Stick with OEM numbers. There are a couple threads on the issue.
 

· Registered
Joined
·
206 Posts
Discussion Starter · #3 ·
Stick with OEM numbers. There are a couple threads on the issue.
For autocross? Nahhhh...

Tire pressure is one of the best and easiest changes you can make to save tenths or hundredths (or thousandths) of seconds. (AND keep from rolling your tires and scrubbing the sidewalls...)

I DID find these below. That's it! Nothing else in autocross. Good place to start and I will chalk the tires.

Tire pressure is so important this thread should be a sticky in that forum...

:shrug:

BlackSS wrote: Just make sure you raise your air pressures to at least 46-47 front/38-39 rear. This will help from rolling the tire over and riding on the sidewalls.

15SuperSport wrote: Thanks man. Make sure your front tires are aired up well, found about 40-42 psi to be good, less seemed to roll the sidewall. Also, don't hit the mute button on the dashcam before the event...

CrashTestDummy wrote this (about a 2012 Caprice 9c1): We ran our '12 Caprice 9C1 at our last regional autocross event. Started with 45#F 42#R and let the pressure drift up with the heat in the tires. I added a bit in the front as the day went on. Ended up with 53#F, 49#R and I think a bit more would have helped. Street tires and the lack of camber, more pressure can help keep what little tread that's on the ground planted.
 

· Registered
Joined
·
602 Posts
Completely stock other than alignment ive been running 36/34 cold. Hot its more like 40/38. The lower rear pressure is helping with rear end grip, I found with anything higher the rear just wants to go wherever when you touch the gas pedal.
 
  • Like
Reactions: Big_Kill

· Registered
Joined
·
1,382 Posts
38/38 cold 40/40 hot. Hate mushy front end feeling with low front pressure.
 
  • Like
Reactions: Big_Kill

· Registered
Joined
·
206 Posts
Discussion Starter · #8 ·
What tires? OEM?
To be honest I'm using the Yokohama all-seasons I bought for the winter. Got the OEMs in the garage - just never got around to getting them put on and now summer is here. With the mild winter we had I'm sorry I even bought the Yokohamas. If I do a real event later this summer I hope to have the OEMs on.
 

· Registered
Joined
·
206 Posts
Discussion Starter · #10 ·
Start at 38 square and go from there. Tighter course = higher pressures. Faster course = lower pressures.
THAT... sounds like a plan. I'll post what happens.

Thanks, SLA!
 
  • Like
Reactions: SLA

· Registered
Joined
·
206 Posts
Discussion Starter · #11 · (Edited)
O.K. here's the good, the bad, and the ugly (not too much ugly!).

Aired the tires to 38 square before I left the house. 40 minute drive to the track. Car sat for at least an hour and a half before my first runs. (There were three groups with probably more than 15 but less than 20 in each group.)

Before I left the house I finally located a piece of chalk to mark the tires at the track, but (here's the ugly, if you can call it that) when I was cleaning up the car a little bit the day before I, for the first time since I bought the car, sprayed a little tire shine on the tires. Of course, when I tried to put the chalk on at the track I got nothing. But I DID notice that the tire shine went above the sidewall on to the curve of the tread, So I figured I would just use that as a guide. And it worked! (More on that below)

First run in Sport mode: 43+ seconds
Second run in Performance mode: 43+ seconds
Third Run in Performance mode with Traction Control OFF: 40.8 seconds

A friend of mine was there running his 2016 Ford Focus RS. He was in the first group and I was in the second. So while the third group was running I offered to take some video of him doing his runs if he would shoot me doing mine and he agreed. So I showed him how to use the camera (Canon SX280 with a huge zoom). It was while I was talking to him I remembered that I hadn't checked the tires. So I went over and looked and the fronts looked perfect! The tire shine was gone right to the edge of the tread to the top of the sidewall. The rears, on the other hand, still had shine on the tread above the sidewall. So I told my friend I was going to let some air out of the rears and then go to my vantage point to shoot his video. Well, I drank some iced tea I'd brought and... completely forgot to air down the rears. Then after shooting the video and they called for group two, I got in line. I was there I realized what I'd done (or NOT done) so I jump out of the car while in line, opened up the emergency key on the fob and let out some air with no gauge or anything. Then I made my runs.

Run One - Perf, TC OFF: 42+ Right from the start I felt like I was sliding all over the place. (It's the first run in the video) When I got back in line I was angry at myself for forgetting to check the tires, what after all my questions on here and everything.

Run Two - Perf, TC OFF: 40.4 So I "chalked up" the first run to the tires being cold... (2nd in vid)

Run Three - Perf, TC OFF: 40.7 (3rd in vid)

When I got back to the pit I put a gauge on the rears to see where they were and the were at 42 pounds (hot).

Then I did my last three runs.

Run One - Perf, TC OFF - 40.3 Best run (for me) of the day. Can't explain doing on "colder" tires as in the first run of the second round except that maybe it wasn't the tires at all and I was just smoother.

Run Two - Perf, TC OFF - 40.8

Run Three - Track Mode, TC and Stability Control OFF and all else for that mode: 44.2
I think with some practice I could get used to Track mode but it IS a different handling beast in that mode. Also, during the event, I "thought" the nannies were kicking in on the big sweeper from right to left on the video, but thinking about it on the way home I started to think that maybe, because I was putting it in second gear (6M) when I got to the first cone after leaving the starting line and just leaving it there, maybe I was hitting the rev limiter! I wish I could go back and try it one more time...

BTW, this was a "low key" event where it is pretty much you against yourself. They don't announce times or anything. But from what I could gather the best times by the REALLY "set-up" cars were in the 35 second range. My friend in the Focus RS finally pulled a high 38 second run on sticky tires. So, all-in-all, I was pretty please with the performance of the SS in stock form on all-season tires. AND I got to drive home in comfort! :grin

Here's a video if you are interested. I think my friend tried to zoom in too much, but he wasn't used to that camera.

 
  • Like
Reactions: airboss63

· Registered
Joined
·
206 Posts
Discussion Starter · #13 ·
Thats a tiny course.
Yes it was. And your point is? Or are you "just sayin?"

The point of the day, as I pointed out, was for newbies to try the sport and for others to get a little practice and to tune their cars. The 50 or so cars there with me all made NINE runs and I could have done one or two more. A normal course for the place is more than twice that big. Where we parked is usually part of the course and the pits are over another hill and participants are led to the course one group at a time.

BTW, I forgot to mention, one of the highlights of the day was when a 7 Liter Corvette blew a piston through the fender wall out on the course! :eek
 

· Registered
Joined
·
206 Posts
Discussion Starter · #16 ·
Reminded me of the "ride and drive" courses at the local auto show.
LOL! That's a good description of the day. Only it was "ride and drive your own vehicle as fast as you can!"
And trust me, there were a couple of people who probably drove the cars at the ride and drive at the local auto show faster than they did their own around that course. (Of course, there was the other end of the spectrum, as well.) The guy there who trailered in a primer grey bug-eyed Sprite with some kind of souped up motor was just incredible. He'd already been racing a good number of years when I first started in 1981.
 
1 - 16 of 16 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top