Bruce0293

Gents,

Issue with 2017 GS running 305/30-19 RE-71 R-square: The traction control is VERY HEAVY handed for the first quarter mile or so with the traction control/active management engaged, and then seemingly it 'learns' and everything is ok. I run with everything shut off 99.999% of the time, however there have been two occasions running in the RAIN in which(2014 Z51) that I was on Charlotte at speed on the banking and infield, and on a long autocross event bumping the rev limiter in 2nd multiple times in which I used track/sport 1. Obviously this is a problem in an autocrossing format, if I to want to use the very limited PTM in Track/Sport 1, and can't drive around before staging.

PROBLEM/SOLUTION: Is there a way to get around this, and/or has anyone had similar experiences and what did you do???

With respect, I'd appreciate knowledgeable answers only, Ok

I am autocrossing mostly, and will track occasionally.

sincerely
Bruce

rb185afm

You need to keep the ratio between front and rear tire. If you run the same height front and rear, you will have issues. I know of no way around it.

Bruce0293

Thank you, unfortunately if you want to autox, the tire to have is the RE71R, and the biggest you can get is a 305. Running a smaller one in the front would require a much smaller tire,

As I said, I have everything off, so I'll just leave it that way!

village idiot

I'm not sure if you have class rules but I run the R888R with 315F and 335R on 18" wheels.

With that said, OEM Cup2 are undoubtedly faster, despite being heavier on a bigger and heavier cast wheel with a skinnier front tire. R888R heats up faster though.

Bruce0293

Unfortunately.... another kink, is in street class(basically no modifications/very limited mods) you have to run a tire with 200 tread wear or greater.... sigh :-)

village idiot

Then run the CUP2. They'll have more traction than any of the tires listed here.

Bruce0293

Cup 2 are 180 Tread wear.

Re-71R, likely have better traction for autox

village idiot

Crap, well, in that case I have nothing to add here and apologize for wasting internets.

bcpower

I’ve run 305/19 square RE-71s for a year and a half now. Occasionally I’ll have TC issues when I first swap from my stock 19/20 wheels to my 19/19 autocross setup. It takes a few miles on the road to get the tire pressure sensors talking to the car correctly. I’ll inflate my 19/19 wheels to 36psi or so and watch the pressures on the dash, once they change from 30ish to 36psi I know I’m good. Once the sensors are talking correctly, I have had no issues in any PTM mode on track, autocross, or street driving with the 305/19 setup.

Kent1999

Side conversation: What width and offset front wheel are you guys using to fit a 305/30-19 tire up front without major rubbing?

Bruce0293

First, thank you...

When autocrossing and once at the event, the car will sit for an extended time prior to first run, and the is no good way to drive it around?

Do the sensors have to re-learn every time it is started with the square set up?

Bruce0293

No rubbing issues with the Re-71R's. Their section is slightly wider (12.3 vs 11.4, from info off of tirerack, and .4 overall diameter larger) however the tread width is the same as the Pilot SS.

SCCA rules state that the offsets can move outward by + 5mm for class rules, and you need to run factory 10" widths. However factory widths and offsets will work fine. My first autox will be this weekend, but 5 miles of street show no signs of any rubbing. (just got them mounted on car and have had no time to drive it)

bcpower

No, you have to get the sensors to communicate once. This is true for everyone I know that has a C7 and multiple sets of wheels.

bcpower

I'm using replica wheels 19x10 +40 front and 19x12 +59 rear. No major rubbing, they do rub a little on the inner fender liner at the top of the wheel where it meets the fender.

fleming23

For Autocross!? Both of those are pretty terrible choices for that kind of event. If he were doing track days, I would agree with you.

village idiot

Just curious, why?