I know its not ideal, but since I have it laying around...
I'm considering burning up my old 275/35/18 R-compounds all around for my new to me 2004 996 AE.

Will 275/35/18 clear the front fender during cornering? I know they'll fit the wheel as I have them mounted on 18x8s currently.

Will having the same size tire (275/35/18) on different size wheels (18x8, 18x10) work?

If not, whats the recommended tire sizes for the 996 in A-stock?
255/35 Hoosier front? 245/35 Kumho V710 front?
305/30 rear? or less tire (285/30) in the rear to compensate for understeer?

Thanks!

 

I think the 275 will not clear with stock wheels and suspension. Having the same size tire on the 18x8 and 18x10 would work if there was room and if you could get the 275s mnounted on a 8" wide rim (which I think is really pushing it). I run 255/18 Hoosiers on the front of my 987 Boxster on a stock offset 8" rim. There is plenty of room for that tire. But I understand that 986/996 had less room in the wheel wells so you might have issues. Sorry I can't give you absolute answers for your 996.

Looks like you are going to have to buy at least 2 tires. Also please do not waste your time mixing brands or compounds. Either go with Kumho v710s or Hoosier A6 at both ends. Personally I like Hoosiers better this year (and last) and if you look at National results you will see that almost all stock class cars are on Hoosiers.

 

Correct me if I'm wrong, but I think the V710 is a better R-compound for camber challenged cars like my 996 AE. However, the biggest V710 for the front is either 245/35/18 or 285/30/18. In contrast, Hoosier has a 255/35 which is probably the ideal size, but not ideal compound/construction for my poor camber car...

I saw reference to someone else successfully using 275 on a 996 front. Just curious if that would work on autox too. I would like to reduce understeer as much as possible...

 

The Solstice guys have run 285s and even 295s on their 8" wheels, so 275 on an 8" wheel should be doable. I'm pretty sure Falkner managed to wrestle 285s onto his Boxster's 7.5" fronts at one point.

You hear this a lot, but I ran a Hoosier / Kumho mix on a 968 for several events (not by choice), and it seemed to work just fine. My codriver won the San Diego Tour by almost a second, beating the guy who won Nationals that year, on Hoosiers in front and Kumhos in back.

 

Hoosiers are still as fast (probably faster) on camber limited cars as Kumhos, but they tend to cord their shoulders pretty quickly unless you run really high pressures.

 

my car is narrow body 997 C2 and wide wise it should be almost same as 996 (I guess).

for stock carrera classics rims which are 18x8 and 18x10 I run on hoosiers a6
245/35ZR18 fronts and 295/30ZR18 rears, rears fit is a bit better than fronts.

255 fronts will not fit on 8" rims. even with 245mm clearance between strut and inner tire side is minimal.

 

295mm on a 8" wide rim? why not 345mm? why stop so early?

 

At some point, you get diminishing returns. One of the BMW guys in our club put two sized tires on the same rims, IIRC it was 285 vs 315, and did a bunch of semi-scientific tests- he found the 285s to actually be quicker. There's more to the dynamics than just tread width; the extra weight (sprung rotating weight with a long lever arm) hurts acceleration and braking, and the cantilevered tirewall geometry and lower pressure makes for sloppier transitions. It's always a compromise, but you've got to find that sweet spot.

 

The tire will fit on the rim, but I don't think your tire will clear the fender.. and since you don't mention your suspension settings, I wouldn't try it. I've seen 255's and 245s fit up front but nothing larger.

 

Well, I guess you can teach an old dog new tricks. My co-driver feels the car understeers too much on corner entry (I think its liveable) and we have done all the legal adjusting we can think of to reduce it.

PedalFaster's comments made me realize the one thing we have not done is go wider than 255s in the front. So, I am doing a $600 experiment by buying a pair of 275s for the front. We should be able to do back to back comparisons. I'll let you know about fit and performance in a few weeks.

 

The best tires right now seem to be the Yokohama Advan Neova AD07, Bridgestone Potenza RE-01, and the Dunlop Direzza Z1. I'm looking for a 275/40R17, but none of those come in that size. Any recommendations for a tire that is comparable to the above that comes in 275 size in 17"?

car covers

 

You're a bit out of date; these things change very fast! AD07, RE-01 and Z1 are all obsolete now, with faster successors replacing them.

The top-tier autocross tires right now are Yokohama AD08, Bridgestone RE-11, Dunlop Z1 Star Spec, Hankook RS-3 and Kuhmo Excsta XS. Which one you get really depends on your needs, as all are capable of winning on any given day, but have different pros and cons. The Kuhmo sucks in the wet, for example; none should be driven below freezing, but AD08 has a specific warning about cold temps the others don't have, etc. If this is just for daily driving and you'll be running r-comps, there's a slew of others that are pretty good- Sumitomo HTR ZIII comes to mind.

 

Sjfehr, can you elaborate on this, I'm about to buy some new street tires and have ruled out the bridgestones because of cost and pretty much ruled it down to the dunlops and kuhmos from the results of the GRM street tire test a few months back.

 

Generally speaking, Kuhmos XS have turned in the fastest overall times in most tests. They seem to have better lateral grip while Dunlop Star Specs seem to have better turn-in and straight-line accelleration/braking. (Dunlops turn in faster times in the slalom, but give it up a bit to the XS in sweepers.) Temp-wise, Dunlops like it cold, and give full grip (or damned close) on the first run, while Kuhmos have to warm up. Dunlops are very good in the rain. Kuhmos... aren't. FWIW, I run Dunlops in PAX street tire class.

Hankook RS-3 is also in this price-range and worth considering. Quoth a friend of mine who ran them back-to-back vs Kuhmo XS:
"-both LOVE heat! Back to back fun runs saw much better traction than a normal event "run cycle" and neither one got "greasy" no matter how many runs I did.
-The XS is a very nervous tire in the rain...even at highway speeds and HATES puddles. (in this regard the MX was much better than the XS) The R-S3 does well in the rain.
-The R-S3 is much better in both braking and acceleration and is more predictable when it does brake away in a turn. Both tires have similar lateral acceleration to the NT01...when all are hot."

I put together a big post at autocross.us a few months ago that might interest people in this thread, too. It's all still current. Nevermind all the guys trying to get me to run R-comps

 

Thanks for the info Sjfehr, I was 90 percent sure I was going with the XS's, now I'm not so sure.