TRAKCAR

I'm with manifold on this one.
No more R6 too dangerous for me.

Manifold

R6 failure rate seems to be higher than other tires, even if most R6 aren't failing (ie, risk is elevated, not 100% or anything close to 100%). For cars driven on CW tracks, left rear tire seems to fail much more often than the others and of course the rear of a 911 is particularly heavy. So I personally wouldn't use the R6 in any car, especially a 911, not worth the risk IMO.

This isn't to say that other tires can't fail catastrophically - they do, and I've seen it with various slicks, R888, etc. So it's highly recommended that tires be carefully inspected before every session; by doing that we've caught some problems that could have resulted in serious incidents. Also important to make sure that the alignment is set up right for the given tire and car, and some tires are more sensitive to this than others (R6 does seem sensitive to it).

I hear that an R7 is coming, which will hopefully be more reliable than the R6.

paradocs98

Sorry to take the thread on a bit of a tangent, but this is interesting and important info. What exactly is happening with the R6s? Is it tread separation, similar to what was occurring with the Nitto NT01s a couple of years ago? If so, I learned at that time that different R-comps have a certain recommended mounting position on the car, even though they might appear to be symmetric in tread design and/or non-directional. It depends on the tire, and depends on whether the car is rear-wheel drive, front-wheel drive or AWD, and the engine location.

Manifold

Tread separation appears to be the most common failure mode, but I've also heard of and seen shoulder rupture, as in this extreme example: http://www.trackhq.com/forums/f13/ho...-failure-6146/.

I don't want to be alarmist about this, most people will use the R6 without having a failure. But with the failure rate appearing to be higher than average, as a risk management practice, I personally wouldn't use the R6 in a 911 nor probably other cars.

And from a risk management perspective, the higher the speed when failure occurs, the worse the likely consequences, so in a car as fast as the 991 GT3 I'd be especially careful in choosing tires, brake pads/fluid, safety equipment, etc.

paradocs98

Understood. So what would be considered a safer alternative for those looking to go beyond the Pilot Sport Cup 2 or PZero Trofeo R? Would it be Yoko slicks, or Michelin slicks, or Continental CTSCC takeoffs? Are any of those even available in 19" sizes?

Manifold

Others may know better, but I suspect that the SC2 and Trofeo R won't have the same grip as the R6. If you can find slicks in 19", IMO they should generally be more reliable than the R6, though also consider the effects of higher loads on the suspension, brakes, wheels, etc. Not sure if any other semi-slicks similar to R6 are available in 19" (I use 18").

Personally, I've been happy with the Nitto NT01s. They're not too expensive, last a while, decent grip which improves as they wear (don't seem to really heat cycle out), not overly sensitive to pressure, and not overly sensitive to alignment.

frayed

how are the nittos grip wise compared to the michelins? the trofeos are supposed to be a bit better than the michelins

paradocs98

I went through 3 or 4 sets of NT01s on my M3 and really liked them as well. Ironically, though, it was the threat of a tread separation issue with the Nittos that led me to the new Toyo Proxes RR instead in my last track season with that car:
http://www.m3post.com/forums/showthread.php?t=810859
I haven't tried Pilot Sport Cups or Sport Cup 2s, but on my 2011 M3 the Nittos were a tremendous improvement on the track compared to Michelin Pilot Super Sports. The NT01s were an order of magnitude grippier, and yet still communicated when they were ready to break loose.

Manifold

I haven't used the SC or SC2 myself, only ridden in several cars that had them. At their best, I'd estimate that the grip of the NT01 and SC are similar, but the NT01 seem to be closer to their best longer than the SC. Presumably, the SC2 is better than the SC, and the TR may be even better than the SC2.

I've seen data around RL which should pin all of this down better, but don't recall where I saw it or what the exact results were.

hf1

Even if the number of R6 failures may be larger that wouldn't mean that its failure RATE (per miles driven) is larger than in other tires. Anecdotally, hoosiers seem to be everywhere any random track event or race. Would be hard to compile any stats on this, I guess.

Manifold

Valid point, and my working conclusions are based mainly on anecdotal info. Wish I had solid data which could be meaningfully analyzed statistically, but I don't. That said, a disturbingly high percentage of people using the R6 have told me they've experienced various types of failures with the tire, some of them repeatedly, which does suggest a failure rate which is above average. So my personal decision is not to use the tire myself, advise others to consider other tires, and advise those using the tire to inspect it carefully and frequently.