Yomi

Really two questions here -- race tire option and street tire option. Car is a 2004 996 C4S, completely stock, with no interesting options. Car runs in AS, and I'm competing regionally, not nationally. We do not have a street tire PAX adjustment unfortunately. I'd really prefer not to do race tires this year for a variety of reasons, but I realize that is a huge penalty. We really don't need to get into street tires vs. race tires unless it's particularly relevant.

The stock car is 18x8 ET 50 front with 225/40-18 tire, and 18x11 ET 45 rear with 295/30-18 tire. Using my trusty hand to measure with the stock Pirelli Pzero, the fronts are extremely close to the strut (a finger width at most), while the rear has lots of room. Note also this is a C4S so the tire diameters need to be reasonably close front/rear.

Since I'm in stock, I need to keep the stock springs (high ride height and all) and stock wheel size (offsets within ~6mm of original). I could toss finances to the winds and do PSS10 or X73, go to BSP, and have my choice of wheel sizes, but I'd prefer to not do that this year if I can help it.

If I did race tires, I'd prefer the V710 for budget reasons, but now I'm looking at square-vs. rounded shoulders and not-quite-right sizes. Either 225/40-18 front and 305/30-18 rear with square shoulder, or 245/40-18 front and 315/30-18 rear with rounded shoulder. Possibly requiring some fiddling to get the fronts to fit, assuming they ever will. Thoughts are welcome.


Now to the fun part. Street tires. Assume that I want to run a single set of tires for both street and autocross, so they'll have to handle all weather other than snow/ice. I only put 2-4k miles of street driving on the car each year. I've read sjfehr's excellent thread on autocross.us, as well as the 2009 GRM articles (I let my subscription lapse years ago). Most of the recommended tires don't seem to fit a widebody:
Toyo R-1R: max width 265/35-18
Bridgestone RE-11: max width 275/40-18
Dunlop Star Spec: max width 275/35-18
Hankook R-S3: max width 285/35-18
Michelin Pilot Super Sport: max width 285/35-18

Some that do (most with 295/30-18 rear, and choice of 225, 235, or 245 front).

Sumitomo HTR ZIII: ~$680 The price is a big plus. Seems like a nice sporty daily driver tire, but by most reports it plain isn't an autocross tire.

Hankook V12 Evo K110: ~$650 same as Sumi.

Michelin Pilot Sport PS2: ~$1400 If I was looking for a sporty daily driver tire I might consider it, as I really like Michelin tires for street driving. But price is so high and it just isn't an autocross tire.

Kumho Ecsta XS: ~$910 Seems to be a great tire in the dry, but most reports say it's nasty in the wet. While I'm not in Seattle / Portland, we still do get enough rain here for me to care. It'd be a different story if I were a serious ST racer and brought a set each of hot/cold/wet street tires to each event. Also, I'd have to shoehorn 315's on the back and 235's on the front at minimum due to a hole in their lineup right where I am.

Yokohama Advan AD08: ~$1100. At first I was put off by the price (heck I still am), but everything I've read has been very positive about these tires.

Toyo RA-1 (full tread): ~$1350. These tires used to be cheap, but they sure don't seem that way in my sizes. One big advantage is that they'd be much faster autocross tires than any of the true street tires. Doesn't heat cycle out nearly like autocross R compounds do. Wet performance should be great as long as they still have tread. However, any R compound is dubious for the street, even with as little driving as I do. Also, I am wondering how well the RA-1 really is vs. something new like the AD08. My personal experience is that the RA-1 is two seconds faster than a Falken Azenis for a typical 40-60 second autocross course, which is huge, but the Azenis hasn't been a top tire for at least 7 years.

Toyo R-888: ~$1100. I'm more dubious about the longevity and streetability of these than I am the RA-1. But, they're a newer tire (the RA-1 is old) and cheaper to boot.

I looked at the Nitto tires, but didn't really see anything I liked (either the tread looked unsuitable for street use or the sizes weren't right).

Any comments? So far I'm leaning heavily toward the Advan AD08s.

balefire

for front tire fitment in the 996/986/987 front suspension, see this:
https://rennlist.com/forums/autocros...s-autox-2.html
i can verify that 245/35/18 V710s fit w/o spacers and no rubbing up front.

for the tire, if i were in your shoes, i would go with kumho xs.
i bet the kumho xs will last longer, and have as much grip as the AD08 w/o the price.
"poor handling in the wet" is a very relative term, that depends on lots of factors. as long as the tread pattern is half way decent (unlike the old RT-215) and the tread depth is decent, i think you'll be fine in the few times your car will be caught in the rain.

gl!

jmyles

Hey Yomi,

I am in the same boat and doing the same research. I agree with your findings. Assuming that I stay with the 295's in the back I am looking to go with AD08's. The performance and price point are pretty decent, albeit I would love something in the $700 range. But I am willing to pop for the extra $$$ if I can be more competitive on the track. I use my 996 as a DD and monthly AX's and once in awhile a DE. I live in San Diego so I can use warm weather tires year round. There are more options if we drop to 285's but I am not sure the I want to go narrower. The other thing to keep an eye out is the difference in the overall circumference. I will keep an eye out and see what you find and let you know what I end up doing.

Joe Weinstein

The RS-3 is the top tire for street tire at the moment. I've raced with the XS and AD08, and
much prefer the feel of the AD08, but the XS came wider for my purposes, so I went that
way.

Yomi

Thanks for all the responses, and nice to see some discussion.

I received some comments from local ST* drivers who have tried both the AD08 and Kumho XS's that mirror what I've heard elsewhere (and is shown in the Tire Rack tests): the XS's are really nice in the hot and dry, but cold or wet they suffer a lot. The AD08's seem like a better all around tire. Price is an issue, but at the sizes I'm looking at it's about a 20% difference -- nothing like the Sumis. The XS's do have a possible advantage for more serious users with the 315/30-18 available for stuffing as much as possible on the rears (close to an inch more section width based on TR specs).

Tire Rack has a 30-60 day backorder on the 295/30-18's for the rear, which isn't good. I'm hoping I'll have them in time for June events, but it'll work out either way. I decided to go with the 235/40-18's for the front. The diameter difference ought not be enough to mess with the diff, and beefier fronts shouldn't hurt as long as they don't rub. I may order some of the ebay 4mm spacers just in case (might get a set of the slightly longer RAD lug bolts to go with them). If I ever get the Victor Innsbruck wheels the fronts would be out 5mm from stock so solve that, and the rears with ET55 would be in 10mm so need the 4mm spacers to get back into SCCA legal stock offset range.

I had almost made up my mind to go ahead and do another set of wheels and race tires, but then started trying to figure out how I'd get them to events. Nothing looked particularly good (we really don't have any place to put a tire trailer other than the living room -- that would be Very Bad for the autocross / family balancing act). So I'll go through this set of tires and work on my driving. Goodness knows that can use improvement

Yomi

Since they're talking AS, this means stock springs, only modifications to the inside of the fender, and stock wheel sizes with offsets no more than 0.25" (6.35mm) different. Camber limited to stock allowances (no camber plates, no slotting, no winching metal parts to bend them).

My 2004 996 with stock 8" front wheels running 225/45-18 Pirelli Pzero Assimetrico tires has less than a finger width of space between the tire and strut. Since I'm unable to get my finger in between, that means there's less than a half inch of clearance. Tire Rack claims they have a 9.4" section width on an 8" rim. The V710's are not as wide (!) with a 9.1" section width in the 225 size. In the 245/40-18 size they have a 10" section width on a 9" tire, the 245/35-18's have a 9.8" section width on an 8.5" rim. I've forgotten the rule of thumb for section widths on different wheel widths, but I can believe this. Based purely on the TR numbers, it sounds really close without spacers, but a legal 3-5mm spacer would seem to compensate for most of the width increase. I haven't a clue on the fender clearance.

With a section width over 2" more (albeit on a 10" rim), I'm incredulous a 285/30-18 fits, even with spacers. I feel sorry for the people trying to mount this stiff-sidewall super-low-profile tire on a rim 2 inches too small for it. I do know the Subaru people fit 275/40-17's on 8" rims -- it looked silly, but that's stock class for you.

Malakas

Interesting thread. Only AX'd my 4S once but it was a blast!

You should check out the 996 Turbo forum to get some ideas of what diameters people run...

I thought the grip from the PZeros was great, but the tire will wear very FAST on the street. Have PS2's now, but have not tracked them yet.

I say you get another set of OEM stock rims, and put MPSC on them for track days...

balefire

is the AD08 rain capability really worth waiting a few months for a tire that is not as wide as the XS you can get now?

depending on your height, you may be able to put all 4 tires in the car. i do + my tools + my wife. but we're short. w/o a passenger, you may be able to fit all four tires regardless of your height.
https://rennlist.com/forums/autocros...ml#post7926967

theory does not always match real world.
i think you can be much more aggressive w/ front tire width.
i've fit in the front w/o rubbing the fender or shock:
245/35/18 V710s on OEM 8"et 50 wheels w/o spacer
245/35/18 V710s on OEM 8"et 50 wheels w/ 5mm OEM spacer
235/35/19 hankook V12 on Volk 8.5" et 39 wheels w/o spacer
in correlation with others from my thread above, i'm pretty sure i could squeeze a 255/35/18 or more with a 5mm spacer up front.
just depends how dangerous you want to be. =)

good luck! here's to hoping more 996s join AS!

Yomi

Ponder... Not sure. This is the car I drive to work in, the car I drive my kids around in, the car I'm taking on convoys around the state / region, the car I'm driving to out of town events in. With these tires on the car. I don't want to have to deal with iffy wet grip on the highway. On the other hand, "terrible wet track grip" might equate to perfectly reasonable grip when driving the speed limit on public roads. Or not. At 30 days I'll only miss one event on the new tires. 60 days is really pushing into some good weekends though.

Could do Kumho XS with 315/30-18 in back (mmm wide), and either 235/40-18 for easy fit, or 245/40-18 (note 40 not 35).

Or screw it and get wheels and V710s (305/30-18 R 245/40-18 F square shoulder, or 285/40-18 R 245/35-18 F for small diameter rounded shoulder), and drive the 15 miles each way to in-town events on them and find someone to trailer them to the out of town events.

I tried without success to get a single 275/40-17 in the trunk. The C4S has a smaller trunk than the 2WD's. Even with the seats far forward it wasn't obvious to me how to fit tires in the back seats, but I didn't try with the seats down. [pause to try it with seats down] Based on the 275, I think I could get two in the back. One in the passenger seat, but then not sure where the other would go. Perhaps it's time to look at roof racks again...

I realized after I posted it that that paragraph of my post wasn't worded well. I was agreeing that after doing measurements, the 245's should be quite doable -- mainly because it seems the Pirelli's are actually wider than V710s of the same size, so give a misleading idea. It's 285's on the front that I still find amazing. Also, again separate out two different things: (1) separate wheels/tires for racing, where I can be as agressive as desired, and (2) single set of dual purpose tires.

Thanks!


With 300+ runs a year, street use (including wacky race alignment) has had almost no effect on my tire wear on previous cars.

balefire

I didn't think about trunk size in C4 996s.
I also didn't think about the importance of tire diameter in your C4.

One 245/35/18 fits in my C2 trunk (w/o spare). Both 285/30/18s fit in the rear seats with the seats up. My other 245/35/18 actually fits in the hump between the rear seats, but barely clears the roof liner.

Smaller diameter:
If you can fit a 245/35/18 either in your smaller C4 trunk or in the hump between the rear seats like me, then you could try fitting the other 245/35/18 in the front seat and 295/30/18 A6s in the rear seats.

Taller diameter:
Similarly, if you can fit a 245/40/18 V710s in the trunk or above the rear hump, then you could run the 305/30/18s V710s.

Ultimately, both the AD08 and the XS are compromise tires. Not as good as R-comps. Not as durable or cheap as other DD tires.
On the other hand, R-comps are certainly a compromise in convenience.

I opted to compromise my convenience. In fact, I didn't know if I could fit all 4 tires when I bought my 40th 996. For my 1st autox I was actually prepared to put 2 tires in the car and drive on 2 R-compounds to an event 70 miles away. Tough choices. Good luck!

utkinpol

for 'street friendly' r-comps if you can fit NT01 - get them. they are better than R888.

I use dunlop star specs for street in 235/275 and like them a lot. for events i have 9"/12" 18" rims so 'streetable r-comps' tires selection is not that great in 255/315 sizes.

I am surprised 996 car can fit wheel into frunk - in my 997 c2 front does not close if I put wheel into trunk. if wheels would fit it would open up A/R hoosiers, v710 kumhos and z214 hankooks.

jmyles

FYI - I bought a set of AD08's yesterday from Discount Tire. They are taking 3-5 business days to get them. The only reason for the delay is that the 295's are coming from Ohio and I live in San Diego. Discount matched TR's price plus they have $40 off on any set of Yokohamas.

kjchristopher

I'm running the RS3s in 245/285 on my 2002 C2. Same tire I campaigned nationally on my STX RX8. (Those same two sets are still being used this year by the current owner.) Wonderful tire. In stock, you can afford to lose the 295 in the rear. Get as much up front as you can.

utkinpol

how do you like them in rain/wet? i read that star specs are a bit better in rain than rs3, is it true?

kjchristopher

I think it is true, but if I were worried about rain I'd go with the Toyo's. (Not sure if they have your size.) I never drove them in actual rain at an event. Just damp. Nor did I run my Star Specs (went through a 1.5 sets of those too) in actual rain.

My spirited 'around town' driving says they are fine. Just can't give you data to back that up (how far off they are).