BERETTA

Those of you that have run the C6Z in low speed autocross-I am running the stock Goodyear Tires. What tire pressures are you finding to work best? Also do you run with the traction control, competition mode etc. off or on? Thanks!

Pylons

C6Z51 here and have never run on the stock tires, so I won't advise on tire pressures.

You want both active handling and traction control off (press and hold the button for ~10 secs).

Datawiz

I've found street tires to work the best with lower pressures vs. higher pressures since the sidewalls are so stiff. The difference between 30 and 36 psi on our half mile test-n-tune track was about 1/2 second. (4.x tenths)

I'm guessing anywhere between 27 and 30 is the way to go. You will just need to experiment. I don't spend much time on street tires, but this is what seems to work the best for me. I did not experiment with different pressures front/back as I do with Hoosiers.

If you are fairly new to autocross, you may consider using Competition Mode until you become proficient with your car. Do note, however, running in competition mode may cause your brake fluid to get hot and possibly boil over.

Once you get good enough and run with everything off, you'll never look back at the electronic nannies again.

Have fun.

BERETTA

Thank you, I really wanted to run on some Kumho 710's that I have but the event is two hours away and really just wanted to drive the car to the event and not deal with a trailer etc.
I agree I think the nannys should be turned off-I have only autocrossed this car once before and I remember quite a bit of intervention from the active handling..Thanks again

BERETTA

Good advice;I have only run this car once before in autocross-I remember running the cold pressures up around 35 or so- I never got a chance to try it with lower pressures I am going to take your advice and start at around 27 cold-I agree the sidewalls are very stiff on these tires and because the speeds are not very high in this type of an event hopefully the lower pressures will help...

Datawiz

FWIW, I stagger the pressures in my Hoosiers. Fronts are 33-34 and rears 29-30. You may try the same thing with the run flats. A little higher in the front, little lower in the back.

Bill Dearborn

I have been playing with pressures to see where the EMTs might actually perform a little better. Have gone from 28 front/26 rear to 35 front/33 rear. The 28 front/26 rear seems to work well on a high speed course but I haven't found it helpful when autocrossing. It may be that everything is being covered over by the tendency of the rear tires to spin without much throttle input. Coming off the line is an exercise in patience, first and second gears can go up in smoke if you are even a little aggressive on the throttle. With my 97 and then my 03Z I would bring the revs up to 2100 ride the clutch just a smidgen as I started and then roll into the throttle as the rear tires bit on clutch out. Can't do that with the C6Z. On a road course where you get it into the higher gears it is just a beast and is just awesome.

One thing I learned about EMTs when I had my 97 was that early style of EMT did not tolerate low pressures. Even at 30 psi cold in the front the tire would develop a wear spot about an inch wide and an inch outboard of the center of the tire. The only way to stop the tire from wearing that way was to keep the cold tire pressure above 35. It was very similar to the 1990s BFG R1 Groove of Doom that was caused by low pressures. I always suspected it was due to the same build construction issue the BFG had. The sidewall was so stiff it caused the weakest part of the tire (the tread) to buckle under hard cornering.

I haven't seen anything like that on the Supercar EMTs. It may be the sidewalls have been softened enough that the tires will not do that anymore, but I have been watching for it.

Bill

BERETTA

Thanks Bill, thats a lot of good information! I run the car today in Nashville, the track was set-up for higher speed than I was used too for autocross. They had a lot of room at Nashville Motor Speedway in the parking lot. I agree the hardest thing about this C6Z is modulating the throttle, it is very difficult to control wheel spin. I eventually got to where I could take off with very little spin, but then I felt like I wasn't into the throttle enough. These cars are better suited for the Road Course, I have only had it one Road Course and it was a beast.