Hi all
I'm looking to buy my first set of stickier tires to use at autocross. I'm looking for 275/40/17 fronts and 315/35/17 rears. I don't drive the car much on the street so in mostly concerned with how the car works. I live 17 miles from the airport we race at.
Thanks

 

The only tires I've seen in my sizes are Nitto NT05's and 01s.

 

Im using Nitto 01's on mine, 275 front and 315 rear,
they work well, especially when fresh, when your buying shop around for the most recent manufacture date on the tyres.
The good thing about the Nitto's is that they seem to keep lasting, my fronts are last years rears and they still grip !

 

The NT01's seem good for a 100TW track day/auto-x tire.

The NT05's suck, much better options for 200TW tires.

What kind of class system are you running under in that organization?

How fast do you want to go?
Hoosier's, BFG R1 S, R888, come in those sizes.

In all honesty, the 275/315 setup is NOT ideal for a C4. You want it square. 275/275 or 315/315 or something close. ALL the Z51/Z07 cars came with a square setup.

 

geforce sport comp 2's here.

they just work for me, they were also affordable and with FE1 springs on Z51 shocks I can still 3 wheel it. practically no traction issues. I'm probably best described as 'ameature+' some seat time, not a great deal, probably not pushing the car enough here to test their limits so they work well for me.

 

I run in NCCC class 2E . I run our tune and test events every month but plan on running a few points events this season. I have been looking for another square set of wheels for a while now but I have an 85 so there's not much available for what I'm looking to pay. The only tires at tire rack in the 315 size are the a7 Hoosier's.

 

Do they make them in the 315/35/17" size? I haven't been able to find um .

 

Interesting. I've got a '92 Z07 that I Auto-X occasionally and I'm now running the 275/315 setup with Sumitomo's. I've found that my lap times have improved over my previous 275/BFG's. Maybe my BFG's were just old and crappy, maybe I've improved my driving or maybe it's just the new tires/wheels provide that much more grip. I dunno...
I will say this: the new 315's look awesome even if they do toss up a lot of crap onto my lower rear quarters!

 

I'm running nitto 555s 300 tw in the same size and my times have also gotten somewhat better but the car slides around quite a bit whenever I try to push it !

 

I'm running a 315 nt-01 square set up. It is WAY better compared to last years 275 nt-05

 

How does the Nitto NT01 compare to the Toyo R888 ?

 

I believe they are supposed to be very similar.

 

For your 85 you can get zr1 reps from afs, they are a little heavy but for the price its a no brainer. I just got a set of 17x11 with nt01 315's all around, ran autocross this past sunday and have to say the tires stick! One issue I did have was getting the tire up to optimal temp of 200*, I had 6 runs and the tires never reached over 120* and i'm a pretty aggressive driver. I may have been running them a little low on pressure, but they are a track day tire designed to dissipate heat so I think they did well for what they are. That said I was 5th fastest time of the day, behind two r-comp cars and two kook rs-3 cars by a margin of .07 and had the tires heated I think i could have got another .5-1 sec out of them. ( http://www.houston-bmwcca.com/wp-con...-event_raw.htm)

As for track days they are awesome, I did a HPDE at TWS and they stuck like glue.

 

My NT05's are great! Still give great grip in the rain, although I'm rather unaccustomed to driving aggressively in the rain.

 

5th place thats sweet! How modified is your 85 ? With my street tires Im usually in the mid 20th place of 40 or so cars.

 

I'm running bilstien ak series shocks, 84 z51 springs, 32mm front sway, zf6, 383. I will probably go back to a nyu rear spring because it oversteers.

 

How much camber you running?
My car understeers pretty bad.

 

I also converted to 315 rears. It's much better than the OEM square setup. I would never return to 275's on all 4 corners.

I've run the OEM gatorbacks, then Nitto 500's (discontinued). The Sumitomos are better than both and cost less.

FYI...I posted about buying 2 imbalanced Sumis a few years ago. Tirerack replaced them -- though I had to reship. My newest set was within tolerance. I also had my suspension bushings/balljoints/tierods redone. Any dissatisfaction with Sumis was compounded by the aging suspension. I'm sure you'd feel an out-of-spec tire but having a less-than-optimum suspension makes it worse.

Sumi seems more proliferated into the tire market now. Maybe their QC is better now too.




(BTW...ZR1s don't have a square setup. FWIW...the rear sway bar is a bit bigger to keep the butt down.)

 

I just bought a pair of 315/35 Nitto NT05R's on a pair of 17x11 AFS rims, but haven't had a chance to try them out yet...

 

I'm not trying to ruffle feathers but go find me a winning C4 in ANY auto-x class that has ANYTHING but a square setup. Good Luck.

These cars NEED more FRONT rubber not rear rubber that will make understeer worse.

ZR1's handle like crap. Soft suspension and nose heavy compared to a standard C4 with Z07/Z51 suspension.

The 84 Z51 rear spring is too stiff and hence nasty oversteer due to the high roll center in the back of these cars.

I wish some of you could come drive my C4. I've got more "your car looks like it rotates perfectly" comments than you can count.

I'll leave some results here for you to ponder. http://stcsolo.com/content/results/2...lts-Event4.pdf

Notice some of those names. Pallotta 3X National Champion, Ferchak, Pearson, Ryan=ALL Trophy level winners at nationals this year.

You don't keep up with these guys without having a "properly" setup car. Yes, I have some driver mod, but not as much as I would like.

http://stcsolo.com/content/results/2...lts-Event4.pdf

Only 2 cars faster on street tires. I beat many others on R-comps in Raw time. My competition Greg Vincent is a VERY good driver (didn't have the results at nationals he wanted but still very fast) 1K custom front bar, and 4K shocks on that S2K. I have factory Z07 stuff and some $600 Koni's.

If you are not running Bridgestone RE71R's or Rival S's then likely your going to be slower than you could be at least with 200TW tires. I bet the RE71R's can rival many 100TW tires. They are THAT good.

You all run and setup what you like but YOUR WRONG IMHO.

You'll notice TurbineSurge is running a square setup. I don't get how the staggered setup is somehow better. The results/experience prove otherwise?!

I'd be happy to share my car's setup if anyone cares.