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Can you win on street tires?


Grant
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As mentioned earlier, my experience with the Z2 shows it falls off pretty significantly after 3-4 hard laps in hot weather (braking grip is the first thing to go). But for TT, that's really all you need anyway.
My experience with Z2s is that they start to fall off by the end of the first lap on hot days If you want to run 205s, why not go with XSs? Are the Z2s quicker when cold?
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Like Walter said, I'm mainly basing my opinion of the Z2 vs. XS on autocross results. I had a set of XS on another Miata, but the setup was nowhere near aggressive as my TTE car, so I can't make a fair comparison. Part of the reason why the "TT on street tires" discussion is fascinating is that so few seem to be doing it. There isn't much available data, at least not that anyone is willing to share.

 

Since I'm not fast enough to have any speed secrets to hide I'll post up my data from Roebling when I get to a computer, and I'll let you know what I find when I test at CMP next month.

 

As for the 3-4 laps thing, my best session on the Z2's came during a roughly 90 degree August day at Roebling (mild for Savannah in August!). Laps 1-3 felt fantastic and were all consistently in the 1:26's (for a car whose best on Hoosiers is a 25.5). Lap 4 I had zero braking grip and locked all 4 coming into Turn 4. After that there was no grip to be had until the tires were allowed to cool for at least 30 mins. I am sure it's possible that the tire would give even less on a hotter day.

 

If not the Z2, then what? RS3? I've only autocrossed on that tire, in a FWD car, but I hear it's inferior to the Z2 on most cars. Rival? I hear it's even less heat tolerant than the Z2. But I don't have first hand experience. And there, I believe lies the problem with the street tire strategy: even if you concede that it's theoretically possible to find enough grip in a street tire to come close to the Hoosier, and the resulting points savings give you enough power/aero/suspension benefits to offset the rest of the difference, I think in practice you will be in a situation similar to the autocrossers in the Street Touring classes - testing, testing, testing the full menu of available tires to find the one that yields the most for your particular car and setup. Also, autocross courses are different every time, but tracks are a known quantity, so that's another variable to consider. It's possible the car likes the Z2 at Roebling but the Rival at Road Atlanta, which means even more testing.

 

Man, I think I've almost talked myself out of this experiment. Hoosiers may be expensive, but this sounds like WORK.

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Like Walter said, I'm mainly basing my opinion of the Z2 vs. XS on autocross results. I had a set of XS on another Miata, but the setup was nowhere near aggressive as my TTE car, so I can't make a fair comparison. Part of the reason why the "TT on street tires" discussion is fascinating is that so few seem to be doing it. There isn't much available data, at least not that anyone is willing to share.

 

Since I'm not fast enough to have any speed secrets to hide I'll post up my data from Roebling when I get to a computer, and I'll let you know what I find when I test at CMP next month.

 

As for the 3-4 laps thing, my best session on the Z2's came during a roughly 90 degree August day at Roebling (mild for Savannah in August!). Laps 1-3 felt fantastic and were all consistently in the 1:26's (for a car whose best on Hoosiers is a 25.5). Lap 4 I had zero braking grip and locked all 4 coming into Turn 4. After that there was no grip to be had until the tires were allowed to cool for at least 30 mins. I am sure it's possible that the tire would give even less on a hotter day.

 

If not the Z2, then what? RS3? I've only autocrossed on that tire, in a FWD car, but I hear it's inferior to the Z2 on most cars. Rival? I hear it's even less heat tolerant than the Z2. But I don't have first hand experience. And there, I believe lies the problem with the street tire strategy: even if you concede that it's theoretically possible to find enough grip in a street tire to come close to the Hoosier, and the resulting points savings give you enough power/aero/suspension benefits to offset the rest of the difference, I think in practice you will be in a situation similar to the autocrossers in the Street Touring classes - testing, testing, testing the full menu of available tires to find the one that yields the most for your particular car and setup. Also, autocross courses are different every time, but tracks are a known quantity, so that's another variable to consider. It's possible the car likes the Z2 at Roebling but the Rival at Road Atlanta, which means even more testing.

 

Man, I think I've almost talked myself out of this experiment. Hoosiers may be expensive, but this sounds like WORK.

RS3's or the aforementioned XS's … both seem to tolerate heat fairly well … or so I've been told … I've been running R1R's for a-x for the last 3 yrs .. before that it was BS RE-11's and RE-OR1's

 

heat usually isn't a problem, since we can spray the tires after each run, and runs are from 30sec to 70/80sec. as opposed to 2 min laps that keep adding on to each other

 

 

FWIW, a lot of the Chump/LeMons folk are using Rival's, and ZII's … the last one I raced with was using Falken's …

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FWIW, a lot of the Chump/LeMons folk are using Rival's

 

Interesting. I can think of at least two "top 20 or better" teams that destroyed Rivals quickly last summer (chunking, sidewall bubbling, etc) and didn't have any problems with RS3's or Star Specs on the same cars.

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FWIW, a lot of the Chump/LeMons folk are using Rival's

Interesting. I can think of at least two "top 20 or better" teams that destroyed Rivals quickly last summer (chunking, sidewall bubbling, etc) and didn't have any problems with RS3's or Star Specs on the same cars.

 

When you say Star Spec are you referring to Z1 or Z2?

 

I knew about the LeChump guys running the street tires but had sort of discounted that data for the same reason I had the autocross results. Just as a good autocross tire might not hold up long enough to be effective in a TT session, a tire that can't last in an endurance race may be fine in TT.

 

I suppose that the new Chump Car sprint races will be a good source of data from that standpoint.

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FWIW, a lot of the Chump/LeMons folk are using Rival's

 

Interesting. I can think of at least two "top 20 or better" teams that destroyed Rivals quickly last summer (chunking, sidewall bubbling, etc) and didn't have any problems with RS3's or Star Specs on the same cars.

Jon, the Golf you were pitted with at the 24hr (Hung South) was on Rival's … it was the second race on them and they used the same tires for at least one more race

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FWIW, a lot of the Chump/LeMons folk are using Rival's

Interesting. I can think of at least two "top 20 or better" teams that destroyed Rivals quickly last summer (chunking, sidewall bubbling, etc) and didn't have any problems with RS3's or Star Specs on the same cars.

 

When you say Star Spec are you referring to Z1 or Z2?

 

I knew about the LeChump guys running the street tires but had sort of discounted that data for the same reason I had the autocross results. Just as a good autocross tire might not hold up long enough to be effective in a TT session, a tire that can't last in an endurance race may be fine in TT.

 

I suppose that the new Chump Car sprint races will be a good source of data from that standpoint.

ZII … the ZI isn't available anymore (that I'm aware of)

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When I say Star Spec I am referring to the Z1. As I am still using up a pile of those on my E36, lol.

 

Anyway, I can think of several who had bad luck with testing Rivals and therefore chose not to run 'em in crapcan races. Same cars driven the same way didn't have problems with any other sticky street tires. It was a different VW and an E30, so not a fwd/rwd thing either. Not saying they're bad, just that some have had problems. YMMV...

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understand the YMMV … a lot of a-x'ers bought into the Rival's hoopla … and have immediately switched back to the R1R's … these are small light weight cars … Civics, CRXs, Miatas … etc….

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Our crapcan has set FTD more often than not, on sets of 265/40/17 Z1 Star Specs. Switching to 255/40/17 Z2s on a 80F day resulted in the same lap time as the driver had run on Z1s, on the first lap. Every additional lap was slower, to the point where the car was a second off its Z1 lap times. The tires were then allowed to cool for 15-ish minutes, and I got in the car. My best lap was 0.54s off my best Z1 lap, which was the fastest the car had ever gone around our test track. This was with no traffic, so every lap was 10/10ths. Data is here.

 

The car is RWD at about 2750 lbs with driver, and makes 205whp.

 

All the R-S3 vs. Star Spec data I've gathered shows the R-S3s to be clearly quicker, though I don't have same-day, same-driver, same-car data. I am not at all impressed with the Z2 or Rival.

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Our crapcan has set FTD more often than not, on sets of 265/40/17 Z1 Star Specs. Switching to 255/40/17 Z2s on a 80F day resulted in the same lap time as the driver had run on Z1s, on the first lap. Every additional lap was slower, to the point where the car was a second off its Z1 lap times. The tires were then allowed to cool for 15-ish minutes, and I got in the car. My best lap was 0.54s off my best Z1 lap, which was the fastest the car had ever gone around our test track. This was with no traffic, so every lap was 10/10ths. Data is here.

 

The car is RWD at about 2750 lbs with driver, and makes 205whp.

 

All the R-S3 vs. Star Spec data I've gathered shows the R-S3s to be clearly quicker, though I don't have same-day, same-driver, same-car data. I am not at all impressed with the Z2 or Rival.

 

This feedback plays into my consideration between running 205 rcomp or 225 street tire next season. Does anyone have thoughts on whether a 225/45-15 Hankook RS3 on 15x8 would be competitive with a 205/50-15 Nitto NT01 on 15x8? This is a 2450# (w/ driver) Integra with around 150HP.

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Theres only about a second difference in my TTC car at roebling between 255 DZII's and 225 A6's.

With the wing its practically flat in T3 and T9 on streets so if a cars got less power and is easy wide open there I think the difference would be less.

 

At road atlanta the difference is 2seconds+ but then gearings definitely a factor there it sucks out of 10b on street tires.

 

I don't think the gap between the new street tiers and NT01 etc is enough to bother with the 7 point tires.

I wish they made a 275 17" street tire for a 10" rim so I could test against a 225 Hoosier.

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  • 2 months later...

How bad would they bust you in points for running a staggered 255/40/17 and 315/35/17 in a Nitto 555 street tire with a 300 tread rating? Just curious

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This feedback plays into my consideration between running 205 rcomp or 225 street tire next season. Does anyone have thoughts on whether a 225/45-15 Hankook RS3 on 15x8 would be competitive with a 205/50-15 Nitto NT01 on 15x8? This is a 2450# (w/ driver) Integra with around 150HP.

 

Depending on the size/length of the track and driver talent I would think the best time would be very similar.

 

Against a 205 RR, however, is another story.

 

An entire session vs 1 lap, however, is another story.

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