rioyellows2k

It's time to get new Rear tires for sure. I'm down to the wear bars on 255/40-17 Dunlop Star specs.I've been fortunate to get very even wear out of them.

I have 8 Autocrosses, and 1 HPDE on them, plus 8,000~ish street miles. I've been happy so far. But as they've "aged(?)" they have really fallen off. At the last autocross they were sliding all over the place and it was suggested that I've heatcycled them because I had daily driven them. Is this accurate? I wouldn't think tread depth would effect dry traction but I could be wrong.

My fronts are still good, plenty of tread, but they are the same age as the rears. If these were all seasons or even a UHP tire like a HTRZIII, I'd feel comfy about just getting a set of rears. But if what I'm hearing is correct I'm mixing old hard Dunlops with new soft ones.

Am I OK buying just 2 rears or should I go ahead and get a full set again?

INTJ

I have the same setup and the same issue. I get much less traction from the rears and the "normal" from the front. The wear is perfect despite the silly high camber, but now in the dry it lets go. I'm above the wear bars by a lot but below the third tread wear groove.

hippo and dog

i'm in a similar situation.... but i havn't been out to the track or autox to test if my tires are gone. i have about 30% tread life left.

i have an upcoming trackday in july... i wonder if i should replace these by then?

Jim@tirerack

As the tires heat cycle over and over they will get harder.

ZDan

I've done four track days on my StarSpecs, and ~10k or so street miles. The rears are past the wear indicators as of I have a new pair waiting for me at the tire shop now (thanks, TireRack!).

Last track day was two weeks ago at Monticello. The tires performed brilliantly in the wet on day 1 Day two in the dry, I was a lot slower relative to the same cars (most on DOT R-comps). On Both days, the fronts and rears exhibited similar grip, despite the fronts having one fewer track day and maybe 2500 fewer street miles on them, and still having half tread depth left. The rears were not to the treadwear indicators prior to this track event, fwiw.

So over this usage, I would say that my StarSpecs still had heat cycles in them, but ran out of tread first.

So I don't think you can heat cycle them out of usefulness with street miles.

I have had (other) street tires heatcycle out on my before, over ~8-10 track days, while still having a lot of tread depth. What would happen would be that they'd have fantastic grip at the last lap of their last "good" track day, but then on the very first lap of the next track day, they'd be utter crap!

rioyellows2k

So....replace two worn rears or all four?

davidc1

Tread depth on the rears affects dry traction massively.

I've had 4 rear sets of different tires, driven them all down to the wear indicators, and when they get down there they lose huge amounts of grip. I slid around everywhere!

It's funny...when it first happened I was confused. I figured that if the tire was becoming a slick, it would increase traction. But for whatever reason, you lose a huge amount of grip, and oversteer all over the place.

rioyellows2k

That's what I'm experiencing, but no one has really confirmed if that's the cause. Still would like to know for sure. Based on what treadlife is left I'm going to try and run one more HPDE on them, and put the new ones on right after.

INTJ

I respect zdans experience, but this is funkt. I know what heat cycled tires feel like (615s, lol) and this is pretty similar, without the greasy. Plus, I'm not at the bars, I'm below the 3 wear grooves in the center tread element, but still mms above the DOT bars.

I just drove these at 0 C in light, non-sticking snow and they were not the suicide ride I expected. Never advised.

I remember the review on the various differentials in Grassroots Motorsports and they had some magical same wear front to back, that would take the guessing game out of this, because I'm still first bar on the fronts. http://grassrootsmotorsports.com/articles/whats-diff/

aCab

I assume you know that driving them in cold weather makes them harder too, right? They won't ever achieve the same performance they had before such an experience.