Trueblood22

I'm looking at stepping up to a little better tire than my 200TW's this year for AutoX in my 05 z51. We run on an old, unused airfield with a relatively low traction, but very abrasive surface.

Has anyone run the Hoosier A's on a surface like this? We're a very small club and have a couple of members on Nitto NT-01's, but noone on anything softer.

Is there any chance of a new set lasting 50-60 two minute runs? I intend to target somewhere around 1.6 front/1 rear camber.

Also, I've talked to and read of some members running some pretty abnormal tire sizes on stock wheels to pick up time, but I'm not sure I'm ready to go that far. Is there a "normal" tire size combo for stock non-z06 wheels? Is there any reason not to go for A7's over A6's?

strano@stranoparts.com

I think you would be unhappy with the wear of A's on that surface. That's coarse, and coarse surfaces are hard on soft tires, the softer the tire, the harder things are on them. Made worse with any slip angle, and with speed comes some slip angle.

I'd suggest R's if you want Hoosier's, or maybe R888's, or NT01's, etc. Maybe even if you can find them in your sizes Kumho V710's

Xian

+1 to Sam's feedback. That looks similar to a local site I run (also an older airstrip). That surface will act like a cheese grater on soft tires. It's bad enough that many folks locally who used to run R's have switched to street tires due to accelerated wear on the R's and "not that much more" grip than they get on the street tire options.

If you're stuck on going with a stickier tire, I'd look at the harder of the options Sam mentioned (in particular the NT01). Besides, if everyone else isn't running Hoosiers then there's less reason to escalate the arms race.

Trueblood22

Thanks for the replies guys! It does look like Nitto recently released a 305/30-19 although I'm struggling to find a place to actually purchase it. The V710's appear to only come in 335 wide for 19".

R6/7's and R888's both seem to have stock and tons of size choices. Looking at our schedule, we only have 5 events (25 runs) scheduled on the airstrip this year. I'll plan on running another 3-4 events on a lot less abrasive concrete, and another 3-4 on a asphalt/concrete kart track. I may lean towards a set of R7's?

Several members are stepping up their game this year, so the arms race has already started I'd just prefer to only buy 1 set of tires per year.

This is 5 runs on a new RE-11 on this surface.

froggy47

That's not even close to the neg. camber that Hoosier recommends for a6 (or r6 or a7 or r7).

You will cord the outside edges in about 20 runs.



Nice corn if that's what it is.

Xian

Yep, here's a front after a total of 12 runs Sunday:







The rears are a little more chewed up from the slip angle across the surface.

ratt_finkel

Driving style has a lot to do with tire wear too. Hoosiers can absolutely get eaten up if you drive on them with too much slip angle. Couple that with an abrasive surface. And yes, you could destroy a tire in 30 runs or less.

That being said. I would expect you could probably get 75 runs out of a set on a surface like that. Before they cord. On most surfaces, you should be able to get 100 runs out of a set. Make sure you flip them every 20-30 runs for maximum life.

I know Bryan Hertweck was able to run 315's in the front and 325's in the rear of his Z51.

Trueblood22

Looks like the Pfadt alignment recommendations are 1.6-1.8 front and .9-1.1 rear for track and street use. Any idea of a better target to equalize wear on both sets of tires?


You're thinking 75 runs out of A's? or one of the other sets recommended?

Xian

I'm ~2.1* front and ~1.1* rear. I suspect you'll want to be more in that sort of range or higher depending on how much you can (equally) get out of the front/rear.

ratt_finkel

On my C6Z we would usually get 75 runs out of the front and 100 runs out of the rear on A6's. I could have extended that had my co-driver not been as aggressive. I think they could have easily last over 100+ before cording.

Street tires should net you over 200 runs easily.

Running wider tires, pinched on narrow rims will help extend life in the case of hoosiers. We saw significantly better wear characteristics with 315's vs 295's or 285's on a 10.5" rim.

I don't have any experience with the Nitto or R888's. But I would suspect they would be good for over 150 runs.

I wouldn't worry too much about being even from one side to the next. Depending on lowering and corner weight. You might see a couple tenths difference from side to side in the front. And that is perfectly acceptable. Rears should be equal.

Xian

Different strokes for different folks I guess. I've always preferred a car with a symmetrical setup vs. one that's a little better one way than the other. I also know of folks who've spent the time to reposition their subframe to even out any side to side discrepancy. This seems like the best solution with the exception of the time/labor commitment needed to get it right.

froggy47

The trouble is, if it's street driven much, the proper camber for a6/a7 will wear out the insides fast in street driving.

A compromise might be about 2.4 neg front and 1.2 neg rear IMO

Each car has it's own best compromise based on the rest of the suspension parameters. Springs, sways, bushings to name 3.