Imp

Stock rims are 8" wide.

As asked earlier how would SCCA handle it? Depends on the competitors. It's technically not a legal tire for any class that has DOT tire rules, but your competitiors may not take issue with it on the local level.

If it's just for fun, a win won't matter and you'd be in a Prepared (not street prepared) or Mod class (not sure which one within those).

If you are going for points/wins in the class... put legal tires on the car and run in stock. Someone elses fun running diminishes at the point someone within the class doesn't want to run by the rules.

--kC

CRX Millennium

iTrader: (1)

At the end of Evo Phase 1 school, the instructors said to us: "Congrats, you guys/girls now suck less". That sentiment pretty much sums up my reasoning for wanting to give Dunlop SSR a try. It is cheaper and faster than Azenis (STX winning street) and longer-lasting than Toyo RA-1, Pirelli Corsa, and Michelin Pilot Sport Cup while subpar to serious autox R-compound.

As for the tug-of-war between fun vs win, I have learned that it is more fun winning than driving like an a#s on the course. So I'm fully prepared to deal with objections raised by competitors next year and will move onto legal R tires after that.

Event #7 and counting...

rx8_250f

I have the ssr's for autocross use in size 245/35/18 on my stock rims. i only have used them twice so far but i felt that tire pressure in the lower 30's worked best. I started out at around 38 and they were not gripping to well. i eventually had lowered them down to about 32 and that seemed to be the best.

mlx8

IMO, it's a mistake to mount a 265 or, for that matter a 255 cross section tire on an 8" rim. For a 265 you need at least an 8.5" and preferably a 9" or bigger rim. FWIW, 235's on a 7" rim is also a pretty poor choice of tire to rim matching. Maybe that explains the 50+ psi pressure suggestion &/or tire rollover problem reported.

tuj

Nah, I have 8" rims (identical to stock diameter and width to be b-stock legal). A guy with a Mercedes coupe was running the SSR's also, in 17" 235/40 I believe, and he was also getting into very high pressures (44+) because of rollover.

CRX Millennium

iTrader: (1)

tuj may have meant running 235/35/18 on 8'' rim since he said stock width to be in compliance with B-stock. As for tire fitment issue, I have seen many instance of wide tire on modest rims in different applications, not just for RX-8. If I'm not mistaken (a rarity), new BMW 330 offers Sport package from the factory fitting 265 on 8'' rim. So in a nutshell, it has been done in the past across all marques.

The key thing is that the wide tire fitment is only meant for short-duration such as competition. Running that very set-up on streets for long-term carries additional risk. Hence, it is not recommended by manufactures for legality and safety reasons.

Razz1

this really happens?

ULLLOSE

iTrader: (1)

You would be wrong to think that. Every T2 Camaro/Firebird road races on 265s on 8" wide wheels. The T2 Mustangs run 275s on 8" wheels. I have also seen the same setup on autox cars. There are also a number of RX8s running the 265 Kumho Ecsta V700 on stock wheels. Then there are the guys with 315s on 9.5" wheels, they are all over the map. We used to run 245s on 6.5" wheels on our MX6. We always found with a wider tire on a narrow rim we ran lower pressure. On our Corvette when we tried a 295 on the 9.5" we ran 10psi less than a 275 on the same wheel.

One the flip side I have also seen 275s on 11" wide wheels in SP/SM cars.

mlx8

Tire manufactures publish lists of recommend maximum, and minimum rim widths for different profile tires. What you can do, vs. should are often two different things. You can drive "q", "r" and "s" rated tires at speeds in excess of 130 mph. Should you? I am pretty intrigued by your information having manufactures putting some pretty wide tires on relatively narrow rims. I've got to wonder if they don't have the buying power to have the tire manufacturer customize the tire construction around the size fitted. It's my understanding for example in Germany, that the tire or tires put on a car have to be certified by TUV to the vehicle.

clyde

depends on who you talk to

Dark8

Thank God we don't live in Europe and have to deal with TUV. I feel bad enough for the Californians that have to deal with CARB!

Remember that we are talking competition as in racing. That means you take most of your average Joe street driver safety requirements and throw them out the window and use what makes your car faster and is legal within the rule book.

TeamRX8

iTrader: (25)

you are mistaken, it's a 255/35-18 on an 18 x 8.5 wheel, and it has very soft sidewalls and a very narrow footprint compared to a race tire 255 width, a Kumho V710 245/35-18 is wider

CRX Millennium

iTrader: (1)

Thanks for the correction. I was indeed misinformed. The official spec on 330i Sport is quoted as:

Front: 18 x 8 225/40-18
Rear: 18 x 8.5 255/35-18
Run-flat

CRX Millennium

iTrader: (1)

Subsequent to completing two autox events after the install of Dunlop SP SSR and new alignment between the events, the car is now running 37f/32r, cold. Optimal pressure is set using chalk method. In high-speed-quick-transition tight turn, 37f will see slight rolling over the first circumferential band on the outside tire.

These tires are not ideal autocross r-compounds due to deep tread grooves and benign stickiness, as expected being HPDE/street-friendly. Having driven >1k miles on public road along with autox, they are surprisingly sure-footed in heavy raining condition, within limit of physics. During competition, the SSR is slippery on 1st run, then reaching working temp on 2nd & 3rd, and becoming greasy on 4th.

While the tire has not gotten me over the usual learning curve required of the newbie, it pits me in striking distance of my primary higher-caliber rival, Honda S2000 running Kumho VictoRacer V700. The other driver is Evo Phase II graduate, while I am of Phase I. So the next season will solely be driver improvement, as my objective for SSR was placing closer to my competitors on a budget.

tuj

I ran the SSR's all season this year and I find that using high pressures for your first run is a good idea. The SSR's heat up extremely fast, gaining their peak grip by the end of the first run. I bleed pressures down as they tend to increase with each subsequent run.

They are excellent track tires, and they handle the abuse of a rookie at autox quite well. I had none of the chunking issues some people encountered. I believe those issues were due to under-inflation. The SSR's like pressure. Its also beneficial to run the rears artifically high to create a bit more oversteer.

I think the SSR's are quite comparable to the Hoosier RS305. I haven't heard of anyone shaving the SSR's, but I suspect they might benefit from it, since they have such deep tread. I had no problems running on the SSR's in the wet at Mid-Ohio earlier this year, even with some standing water on the back straight.

On the SSR's (in 225 no less), I was within 0.7 and 0.5 seconds of my regional rival in an M3 on V710's, so I would say in general the SSR's are giving up less than 1 second to dedicated autox tires on most courses.