bvectra

I'm looking to buy tires to autocross my c4 and have 9.5-17 rims what tires should I get and should I do 285 rear with 275 front
thanks people for the help

Charleston2012

Keep it square, ie 285 all the way around or 275's all the way around. Get Kumho autocross tires, 710's I believe. Cheap and effective.

bvectra

thanks Charleston. I have to run above 140 to stay in stock class the 710 are 30 been looking at kumho ecsta xs are 180 but pricey
any help from people on cheaper but good tires let me know

racebum

get the kumho xs if you have to stay above a utqg 140. the ONLY other tire you should be considering is the falken rt-615k which is a direct competitor to the xs
the xs and 615 are capable of pulling over 1g which is amazing for a non R tire

Charleston2012

I would ask the Road Racing autocross section too. There may be some tires that are stickier than their prospective "rating" Some OEM cars have ratings in the 40's, Ferrari, Boss Mustang, for example.

93Rubie

kimmer

But Falken only goes to 275x40 on a 17" wheel.

Bobzilla

I am in the same boat. I am between the 285/40/17 XS's, the 275/40/17 Nitto NT05 and the 265/40/17 Dunlop Star Spec. The Dunlops measure out (on a 9" wheel) to be wider than the current 275/40/17 Kumho SPT's I have now. Almost a full inch to be honest.

The XS is terrible in the rain and cooler temps. The Nitto's I know next to nothing about and the Star Specs are pricey..... Not an easy option.

I've been auto-x'ing for a few years, but always in FWD econoboxes. Last year was my first year behind the wheel of the Vette. Even with it having leaking head gaskets, blowing oil past the rings, 150k abusive miles under her belt she was still an amazing handful. Be prepared for lots and lots of countersteering, tail out happiness.

justkickin

One more to add to the list is the Hankook RS3. Significantly cheaper than the others mentioned with as much or more grip. The RS3 will absolutely kill the Kumho in the wet, but both are pretty much even in the dry, as long as you get heat in them. The downside of the RS3 is the lack of wider widths on the 17's. Max is a 255. Even still, the cost/benefit would make up for the lack of width IMHO.

I run the RS3 in a 255/17 and a 285/18 on my C5Z16 and they are great. They don't provide as much feedback as the Dunlop, but they do give more grip for about half the money. The Dunlop and Kumho are about the same cost. I drove the Kumhos once as well on a friends S2K and they were grippy, but not the feedback the Dunlop was either. IMO, the Dunlop is the best tire, but the RS3, cost factored in, is the best IMO, even if not in the best size.

All reports on the web say the same thing about the Kumho, to paraphrase, don't even think about driving them in the wet, they are that bad. If you don't drive in the rain, it may not matter to you, your call.

All the contenders you should look at are here:

http://grassrootsmotorsports.com/art...-tires-part-1/

and here

http://grassrootsmotorsports.com/art...-tires-part-2/

Unfortunately GRM couldn't get the RS3 in the right size, so it is not included. Just Google "grassroots +rs3" and you will get a ton of links worth reading.

racebum

i forgot all about the NT05, that's also a competitive tire from what i hear, have never driven it personally though, have the other 3.

as for the star spec. it's actually drive-able in rain

the XS and 615 are not, not really in an enjoyable sense anyway.

as for autocross in the vette, it's different than fwd. with fwd you just use a lot of rear spring rate, keep the front somewhat loose, floor it and turn the wheel.

what gets newbies with rwd and autocross is the rear unloading and having to counter. it costs time. you can address some of this with more front spring rate and more tire in the rear but a lot of it is driving skill. in a lot of cases you're actually faster being on the gas, gliding, turning and back on the throttle than you are versus being all out, then hammering the brakes, then trying to turn. you can brake late with fwd all day and stay quick. try it in a corvette and you'll spin the car around. set your lines up so you can brake light, turn and throttle. totally different style than you would use in a honda.

the c4 isn't a bad chasis to auto-x stock. the only problem with it is the parts are starting to dry up. a lot of stuff is out of production and the new old stock is dwindling.

Bobzilla

^ Yeah, the car is running in SSM. I'm not expecting it to be a nationals level beast. Just something competitive locally on street tires and somethign I can take to a track day and not wait all week for the end of the front straight.

Eduardo L98 1991

Nitto