Autocrossing the EP. What tire pressures to run?

[88fox05si]

On the 27th I'm going to autocross the ep. I am looking forward to this because I am bringing the hatch for the first time.

When I run my VW Fox I run higher tire PSI because they are a tall skinny tire (175/70/13). I can safely set the PSI to 45#.

With the hatch, I currently have some Nitto NT 450 tires. They're ok, but better than nothing (came with the car). Because of the FWD, I plan to set the front tires to 40-45 PSI and the rear tires at 40.
I am concerned that because of the lower profile (205/55/16), and the stated MAX PSI of 35, that I run the risk of a tire blowout.

Any suggestions for auto-x seat time with an ep3?

Thanks


Location-Michelin Proving grounds, Mountville, SC

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[Cheep3]

I would normally say that 45/40-f/r would be an excellent starting point, but if the tire states 35 don't go much if any over that. I typically used to run 45/40 ish with good results but those tires had like a 51psi max. I currently run the fronts quite a bit lower because my Toyo R1R's work better lower, and I now have a bigger rear bar to help counteract the understeer. The 205/55/16 size is normally fine overpressure because it wont get too out of shape like a real low aspect tire will. My advice, try to find a decent set of front tires. Don't worry so much about the rears because they are in my opinion really just along for the ride.

[88fox05si]

I placed 3rd in the novice group. My times, over the course of 4 runs improved. My first run was 71 seconds, and the last run was a touch over 68.

[siege911]

I placed 3rd in the novice group. My times, over the course of 4 runs improved. My first run was 71 seconds, and the last run was a touch over 68.

What tire pressures did you end up running? I run about what Cheep3 said, 45 front/40 rear HOT with my dunlop star specs. The ep3 is a HEAVY car, so you need more pressure to prevent sidewall rollover. I'm not sure if you've heard of this trick, but grab some sidewalk chalk/normal chalk and put marks on the rounded edges of all 4 tires. Start at a certain pressure, and decrease/increase until the chalk only gets rubbed off from the tread area, not the sidewall. Also, make sure you take your pressures hot, as the air will change pressure with temperature.

Post this over in the autocross forum if you want dedicated autocross tips! We need more topics there!

[88fox05si]

Yep, I used some chalk to check for rollover. I didn't have any. The car came with Nitto NT450 "extreme performance" tires, and they performed well for street tires. At the end of the run the tires were starting to get "oily" because they were so hot.

I ended up using 44 in front and 41 in the rear. There as not any time for fun runs, so I wasn't able to get much more seat time or tire pressure adjustments. However during one autox I added no more pressure than what I use from day-to-day. At 35psi in front and 30 in the rear, it was terrible.

I'll find the auto-x forum, and hopefully post pics, should any of them become available ( went by myself).

I suppose I'll be asking about some good tires in a few months. The track realy chewed up my front tires!