Tire Selection Advice Needed (Dunlop Super Sport Race)
 

Hello,

As the title suggested, I need to decide on what is the best course of action
for next Autox season. I will have completed about 10 events for my 1st
season and also Phase 1&2 of Evolution Autocross School by year-end.

Torn between running Kumho Ecsta MX/Hankook RS2 Z212 or Dunlop SP Super Sport Race for my 2nd season. I imagine next year to be still the "Learning Year" and running competitively while shooting for top spots on local-level. Given that, which tire should I pick up NOW to stock up on for next year, assuming they are mutually exclusive?

Whichever the pick is, it will be solely for autox and the commute between event and home. I have a second set of stock wheels that will be shod with either Toyo Proxes4/Avon M550/Falken Grb Fk451 depending on my future whereabouts (NJ/CA). Knowing Dunlop SSR is a R-compound tire in competition category, is it truly that much better than both aforementioned Max Performance Summer tires on RX-8? The objective is to run that tire for the whole season and more if possible, while not lagging too far behind true R-slicks.

Reading the comments on http://www.sccaforums.com/forums/42652/ShowPost.aspx, I am worried that Dunlop may be hindered by inadequate grip prior to being properly heated up, which is a luxury autox does not afford. I know for sure that I am not ready for Kumho V710 (skill/wallet). VictoRacer V700 does not come in 18in while staying in BS. Toyo RA-1 is just as expensive as Kumho/Hoosier and also unproven on autox as Dunlop SSR.

As for tire size, here are the choices (shod on stock wheel):
Kumho MX: 245/40/18
Hankook Z212: 225/40/18
Dunlop SSR: 235/40/18 or 265/35/18 (rubbing?)

Thanks in advance for any helpful advices.

Keep in mind the Dunlop is NOT legal for SCCA solo2 racing. While you may be ok if your local guys are cool you can be DQ if you run them. They have not made enough sizes to be given the ok from SCCA.


Think about the Kumho Ecsta V700, 265-35-18, fits and works fine. Wont be as fast as the V710 but will last longer. Also think about looking for take-offs from other racers if you are on a budget. Do not use smaller than a 245 tire on the RX8.

Yes, I am aware that SCCA requires the tire to be available in 4 diameter and 6 size each if I am not mistaken. Your suggestion about V700 is taken to heart, though they are still about $100/ea more expensive than the Dunlop SSR. I like to use the money saved toward driver's Ed if possible.

May I ask about the "Do not use smaller than a 245 tire on the RX8" comment? Seems to me that any traction gains offered by additional contact patch is offset by increasing rolling drag/resistance in autox environment versus road track. Thank you for being the first to reply and I do follow your threads with great enthusiasm.

The RX8 is a 2700lbs+ car... A 225 is a Miata size tire. You can over heat a 225 very quickly. The wider tire takes the heat better, it also has a bigger patch that will help with forward bite, braking and corner speed. The only time widers is not better is if you get to the point where the tire no longer fits on the wheel good. The 275+ tires tend to get a funny shape when put on the 8" wheel, they also tend you have a lot of flex. 245-265 is just right. If you MUST have the Dunlop go for the 255, cost less than the 265 and will give you more tire on the ground than the 245.

While thinking about what tires to use next year will get you a head start on figuring out what to buy, I wouldn't buy them now. Reasons being:

The tires available for next year will probably be a bit different and a bit better for next year than this year. There are a few tires out there that aren't made in our sizes but would be worth considering if they do become available.

Not all the tires currently available are known quantities in terms of wear, durability, performance, etc. because some are still pretty new. Waiting for general opinions of the tires to be formed by those using them *should* be an aidin informing the purchase decision. Of course, some of us have the habit of not really knowing what we're talking about despite being totally convinced that we do and you need to account for that.

This year's tire models may be discontinued and/or be replaced for next year. Then the question becomes "do I buy last year's tire at closeout pricing or do I take a chance that next year's tire will be better performing and longer lasting?"

Generally speaking, the newer the tire (production batch) the better performance you will get. All tires age. R comps age much faster than street tires. The shorter the time between production to the time you use it, the better. If you buy tires now, and leave them to sit for a year, they will harden somewhat even with proper storage. If you buy a tire today that you aren't going to use to March 2006, the tire will not perform as well as a tire that is manufactured in February of next year. Unfortuantely, for most tires, even if you wait until February or March of next year to order, unless it's a brand new model tire, you can't be sure that the tires you receive won't have actually be any fresher than what you would have received if you bought them today. The question is how much worse will they be? For your uses, as long as the tires are stored properly, the difference probably won't be significant, maybe not even noticeable. It's just one of the many factors to take into consideration as you make your plans.

I think I am one of the few people running the Dunlop SSR's right now, mainly because I can't really afford the Kuhmos. Its a good tire, very progressive. Sort of an intermediate r-compound tire. The first event I ran with them I jumped from 50th to 28th in PAX (in 100+ driver fields). I'm lucky in that we have a road between the finish and grid that I can drive back on weaving to heat the tires up. I find that they get heated up after 1 run + weaving pretty well. My second run usually drops something like 3 seconds and the pressures come up.

So the good:
-cheap
-easy to drive, progressive limits
-won't flat-spot or cord easily
-should last almost 2 seasons

The bad:
-not in the same class as the Kuhmos and Hoosiers
-doesn't heat up as easily as other r-compounds

If you just want to do well locally, the Dunlops are not a bad buy. They give you some familiarity with r-compounds without being overly unforgiving of mistakes (Hoosiers) and the performance is high enough to do well against other people on r-compounds. I've beat several people on Hoosiers in my class and in BSP with the Dunlops, so if you can drive decent, you can probably do well. That being said, if you're up against some good drivers on Hoosiers, you'll need a lot of skill to win on the SSR's.

clyde: Generally speaking, the newer the tire (production batch) the better performance you will get.

Point taken, Roger@TireRack echoed the same comment once knowing I'll be buying the set for next season instead of immediate consumption. He did mention that being a volume tire outfit, the current Dunlop SSR inventory was delivered last Wed. Talking about freshness (between storage at TireRack to end-user, since production date from manufacture to TireRack is unknown).

tuj: Its a good tire, very progressive. Sort of an intermediate r-compound tire.

Glad to see other satisfied users commenting on Dunlop SSRs. I dig up the thread you started at https://www.rx8club.com/series-i-wheels-tires-brakes-suspension-55/dunlop-sp-super-sport-r-compound-tires-58515/. Looks like 255/35/18 was recommended by rx8 250f, compared to your 225/40/18. What is your take on the size to have running those tires given your experience?

As for the current special price on Dunlop SSR that prompted my question in the first place, Roger@TireRack also confirmed that the regular price is also wallet-friendly. So I will definitely be postponing my autox tire purchase decision when the right time comes.

The progressive/gentle nature of Dunlop SSR is also mentioned in http://www.porsche-club-norge.no/pdf/gt3.pdf#search='ADVAN%20A048%20test', found by Spin9K in a recent thread. I found the acoustic warning similar to street tire to be helpful as I am learning driving the car at 9/10th. Readings suggest that the tires should be squealing/screeching, but not screaming nor howling at the optimal working temperature range.

Currently running mid-pack at my local events, pure-stock with All-Seasons. All the top competitors have cars that are dialed-in and running on Hoosier/Kumho. So the expectation of vying for the trophy with the combination of Dunlop SSR and Driver Ed is hopefully within my grasp!

The SSR's do give plenty of audible feedback when you lock them or exceed their limits. You'll want to heat cycle them once before you get them, about 3 or 4 days before the first event you run with them. I don't know what your budget is, but mine was pretty limited for race tires + wheels. If you can afford the Kuhmos and you aren't so aggressive that you are constantly locking wheels and/or sliding, they will probably be a good buy and last at least 1 season. Above posters are probably right about getting the widest size available. Just goes to show that the rep's at tirerack don't always consider things like that.

Whatever you do, taking some of the Evolution schools or equivalent is the biggest improvement in time / $$$ that you can do, followed by tires.

Additional research has uncovered a major cording/chunking issue with Dunlop SP Super Sport Race. See http://forums.nasioc.com/forums/showthread.php?t=721016. While it may have been a specific issue with the Subaru WRX crowds, it brings to the question the manufacturing quality of Dunlops. I would advice tuj, rx8 250f, and om-nc to be vigilant on monitoring the wears on these tires.

So I'm back at square one after all the research. Kumho VictoRacer V700 looks to be the most suitable R-compound considering price/longevity/performance. Since VictoRacer V700 does not come in 18in, Kumho Ecsta V700 will have to do before graduating to V710-caliber. Or Kumho Ecsta MX/Hankook Z212 for second season before switching to R-compound for third.

A bit concerning about the size mentioned by ULLLOSE of running of 265/35/18 V700, since a few posters already had problems with 245/35/18 with V710 here: https://www.rx8club.com/rx-8-racing-25/issues-mounting-kumho-v710-61742/. Are oversized V700s easier to mount than V710 on the stock rim?

I'm about 6 heat cycles in on the Dunlops and I haven't had any wear issues yet. I'll keep watching for any chunking, but it would really surprise me if that would happen in an auto-x environment with these tires. They seem like they are geared more towards road-racing, so I would think the compound would be resistant to that.

In any case, they weren't enough for me to beat a 350z in my region, who was on RS305s last event. :(

any tire will cunk under the right conditions, it usually is a result of overheating; low air pressure, insufficient alignment settings, and poor driving can all be part of the problem. The compound is not soft, certainly not as soft and as heat sensitive as the best autox tires, or even the best road race tires. I don't see it being a manufacturing issue.

Update: I ended up picking up a set of Dunlop SP Super Sport Race, 255/35/18 this week. Running against other highly modified cars with R-compound/new Azenis that are inappropriately classed the same as me is just not fun/fair. Having said that, the all-season radial is just one part of the problem, with the other one squarely shouldered on the nut behind the driving wheel.

Research thus far indicates that Dunlops are slightly faster than Falken Azenis and Toyo RA-1 on autox. So it should be competitive enough for local-venue but not R-worthy to mask my bad driving. My question is: knowing it is not legally listed as an approved tire by SCCA, how would local SCCA treat the situation? I run mostly with non-SCCA club this year, though may be forced to go with SCCA next year due to availability around Bay area. I'm not fast/consistent enough to draw attention/protest from seasoned racers, but am just wondering about the implication.

Any suggestions on what F/R pressure (cold) to run them at? I will follow the chalk procedure, but am curious about the initial setting?

ps. TireRack rep confirmed that the tire would still be offered next year despite the big "closeout" sign next to Dunlops. The tire is not marked "discontinued" in the system, yet...

anyone have a pic of a chunked tire?

run them at 50 or higher. My fronts were still rolling over at 47! I run 52F/50R now. The sidewalls are not that stiff. They actually grip incredibly well after 1 run or some aggressive weaving to heat them up. Pretty surprising considering they are a track tire. Runs 2-4 are usually pretty good for me, then they start to go away a little. I have 50+ runs on mine and 1 trackday and the grip level seems about the same. On the track I ran 43F/45R and that worked well.

Also, I am running the 40/235 tire, not the 255 (because I am both stupid and cheap).

52/50? Wow! That's quite a stretch from the info gathered here: https://www.rx8club.com/series-i-wheels-tires-brakes-suspension-55/dunlop-sp-super-sport-r-compound-tires-58515/#post855969. I was under the impression that r-compound needs less air pressure than street tire. We are talking about PSIs that are over Hoosier's territory. Can you please confirm and provide a run-down on your experiment/experience?

Remember, these tires are quite different from Kuhmo's / Hoosiers. These are track tires, not autox tires. I am running 235/40/18, which is as narrow as the OEM tire. Its quite easy to verify that anything less than 50 in the front results in lots of rollover. On the back, rollover was about perfect at 47, but I like them even a little higher to try to get the back a little looser.

Put some chalk or glass marker on the treads and see. I've tried lower and it was a disaster. These tires need high pressures. The few Porsche guys running them in Germany confirm this.

HUH???

FWIW, the Dunlop Super Sport Race is a true DOT-R tire with a 60 treadwear rating, the Falken Azenis is a street tire with a 200 treadwear rating




.

Thanks for the air pressure setting! I will experiment a little and see how it goes at the next event running Dunlop for the very first time.

Yes, I am aware of the distinction between Dunlop SP Super Sport Race and Falken Azenis. The problem is the local clubs have an open-class structure, which categorize cars by hp-to-weight ratio and assign points for certain mods. The reality is people get away with a lot of stuff that would have been penalized under SCCA guideline.

CRX Mellenniium ~ FWIW, I'm now on my 3rd (and 1/2 half) set of Dunlop SSR's. I've moved up from the original 255/35x18's to a set of 265/35 x 18's. In two HPDE track weekends now with the larger 265's, I've not seen or experienced any rubbing issues, although I suspect if either of the front wheels ever got loaded up enough, or hit a bump, they now look to project far enough out of the wheel wells (i.e. past the right & left edges of the front fender lips) that they would "rub."

As for tire pressure, I haven't been very scientific in my approach. I simply started with the tirea at slightly over the stock 32 psi cold ~ @ 34 to 35 and monitored them when warm. I don't know what this ".... 50/52 psi..." business is all about. I assume that CAN'T be a cold starting pressure. In July at PPIR (a NASCAR banked oval track with a short infield road course) located near Colorado Springs, I found myself bleeding air out of the tires to keep them in the 40psi HOT range, running slightly less pressure, say @ 2 to 3 psi less in the rear compared to the fronts. It's been my understanding that you should NEVER run a tire, hot or cold, at a pressure close to or exceeding the max pressure recomendation ~ which in the case of the 255/35x18's is 51psi!

FWIW, I ran into a Dunlop Tire test / support team last spring doing tire testing (not SSR's however) at a track in Nevada. If I understood them, and that's certainly not a certainty, they suggested with a substantially wider tire, one ought to start out with a lower than stock recomended pressure (in this cas 32 psi cold ~ they thought someting like 26 to 28 psi), a tire pyrometer, a good pressure gauge and stop watch or timer and work ones way up in pressure. That's the way they were handling their tests etc. with the race tire setups, lowering not raising pressure.

HTH, let me know if you come up with any better data. I haven't been doing any autocross with the car, just track days. My biggest issue has been the fuel tank / fuel starvation at increasingly higher tank levels in long, high G sweepers. My next issue with the tires along, may be their effective diameter. SSR's are not, so far as I know available in 255/40x18's, which are a much closer equivalent diameter to the stock 225/45x18's. The 35 profile tires are @ 4+% smaller in diameter. The 265 & 255 presently seem to put me right at redline in 3rd gear for some of the corners. I'm considering going to 255/40's to see if that might solve some of the gear choice selections I don't want to make.

HTH someone. Cheers
mike

Remember, I am running the 235's. Yes, 50-52 are the COLD starting pressures I use. I try to release some pressure as the tires heat up and keep them under 54. Yes, I know the max on the tire is 50 psi cold. Anything less than 50 and they are rolling over in autox.

My last count of Dunlop SSR owners piloting RX-8 is 5 including myself. Thanks for those who responded to my request about pressure settings. The following excerpt is the response received from "om-nc", another gracious RX-8 driver:

Reading on SCCA forum suggests pyrometer is used to determine optimal camber while sidewall flex/roll-over is used for air pressure tuning. Good pyrometer (probe not IR-style) needs to be combined with g-meter, timer, tire gauge, skip-pad, and a consistent driver to make meaningful interpretation/analysis of the data.

tuj: Was there a significant change of performance/handing modifications on your car since your previous post at: https://www.rx8club.com/showpost.php...9&postcount=6? Your current setting is seen as the outlier in the whole scheme of things.

mlx8: Very useful info on the reference of proper racing tuning in your encounter with Dunlop factory team.

Fact: There is no magic air pressure setting, and it really depends on one's driving style (overdriving, sliding, smooth, etc...). I will be sure to report back with my datapoints after 9/10.

mlx8: Are you running those sizes on stock wheels, or aftermarket?
I was curious how wide of a wheel the Dunlops really needed for a given dimension.

I do HPDE events almost exclusively. My dear-departed Sport Cups finally wore out on me last weekend, and I've been tempted by the Dunlops, especially given the price of them (half of my Sport Cups.)

Friend of mine got a set of the SSRs on his M3 and is very happy with them.

I also use the SSR for track days and for the money I am quite happy with them. They also perform quite well on wet tracks. I have the 235/40/18 mounted on OEM rims (18x8). The pic is from Pocono (north track)

I am running some aftermarket wheels, but they are 7" wide I believe (whatever is same as stock to be legal in b-stock). Remember I AM ON 235's! (because I was stupid and took the first thing the guy at tirerack offered me).

The only modification to my car is an RB front bar. On the track, the car is quite neutral, on the autox, it tends to understeer quite a bit. I am not a great driver by any means, but I can usually pax in the top 1/3 or so out of 100 drivers. At first I couldn't believe the pressures I was running to get them to stop rolling over. I doubted myself, but I've confirmed it multiple times with both glass marker all over the treads and sidewalls, and via pictures of my car on course.

Attached is a pic of the car running 42 psi. You can see the tire almost coming off the wheel!