Whats the difference between R compound to slicks?

[Stephen31201]

I searched and didn't have a lot of luck finding a post. I am currently running r888s in 275/40-18s and I am contemplating switching to 18x11s square set up that Vorshlag has listed and 315 R7s. I am just curious if anyone could comment who has made the transition from R compound to slicks and can tell me the difference it made. I switched from RE11s to r888s at VIR and knocked off 9 seconds from that switch alone. Investing another $3k in wheels and tires would be a little easier if I had some data to back it up. (Not to mention these GT500s are heavy! 29lbs each. Im sure 8lbs of un-sprung weight removed off each wheel would make a difference). Thanks for the help.

 

[Sky Render]

Clarification is needed. Anything that is for race use only is often colloquially referred to as "slicks."

 

[Stephen31201]

Switching to something that has no tread pattern and a treadwear rating of 60 or less.

 

[csamsh]

Real race rubber (Non-DOT slicks) don't have to be DOT rated. So probably no steel belts, lighter construction, etc. Literally zero considerations towards road use. Probably more finicky to set up around, and more expensive to run.

The DOT R-Comp set (A7, R7, R1, R1S, V710, etc) are still technically DOT approved. The notches or grooves in the tread is just a superficial facet of their "street legality." The difference in actual carcass construction probably shares more in common with a "regular" street tire than is does with a "real" race tire. The tread compounds are still sticky more like a race tire though. The treadwear ratings should NOT be taken to represent any mileage one can get out of them. Personally I would not use any tire from this set in any but a competition setting, as the (cost+headache+being a tire nanny)/fun ratio is much too high unless there is a prize.

The "Second Tier R-Comps" (NT01, R888, PS Cup, P Zero Trofeo) are more like a street tire in all respects than the "true" R-comps. Good track day tires but useless in most forms of competition, as they're not fast enough to compete with the tires listed in the above paragraph, and they're too low of a treadwear to be considered for most "street tire" events.

 

[ddd4114]

I recently moved from 275mm Nitto NT-01's to 245mm R7's, and my lap times consistently dropped by ~4 seconds on average. I found that the R7's were worth ~0.1g in cornering and in braking, and that's why there is such a large difference in lap times. Even with the reduced width (needed due to class rules), I never experienced any significant overheating issues even with my race weight of ~3770 lb. However, the compromise is much less feedback (both audible and tactile). Even still, they are easy to drive, and when you start to slide, it's not that much more difficult to recover.

If you're looking to compete, the R7's (or A7's if you're hardcore) are definitely worth getting over any "lower-tier" R-compound tire. However, for non-competitive track days, I would still suggest using your R888's. They might be a little slower, but they will last much longer and will be more consistent over their life. Real slicks (Pirelli's, etc.) will offer even more grip, but as usual, it's not a free lunch.

 

[Pentalab]

I recently moved from 275mm Nitto NT-01's to 245mm R7's, and my lap times consistently dropped by ~4 seconds on average.

That's a huge amount...and on a tire that's 30mm narrower. The NT-01 is no slouch either.

 

[Stephen31201]

Thanks for the insight! Someone actually making the change from one to the other is what I was looking for! Just wanted to justify the difference in order to shell out the cash.

 

[Mark Aubele]

A 245 R7 is likely the same width as a 275 Nitto or very close.

 

[modernbeat]

Having gone from Falkens to Bridgestones to R6 to A6 to R25A to R25B, I got faster with every switch. The big swap from streets to Hoosier DOT-Rs came with a huge decrease in tire life, but better consistency. The fall off in street tires was noticeable, but small. The fall off in DOT-Rs was huge. When I switched to Hoosier slicks, which were lighter and much stickier, alignment, temps and tire pressure became much more critical. Performance went up, but the fall off once the tires cycled out was even larger than the DOT-Rs. Enough that the tires weren't just slow, but I considered them semi-dangerous.

 

[ddd4114]

A 245 R7 is likely the same width as a 275 Nitto or very close.

Yeah, they're fairly close. I can take measurements this weekend, but I'm guessing that the real difference is only ~10mm.