Carpokes

I’m running Nankang CR-S tires this year and I’m curious how many track days might be left when the grooves are gone. I’ve worn tires to the cords in the past but I’d just as soon not do that. I realize this probably isn’t measurable and any estimates are just that. Still it might give me something to go on.

I never used Nankang, but my track and autoX experiences with Toyo, Bridgestone, Khumo, Falken, Avon, Goodyear and Michelin track tires are similar: grip disappears long before the grooves (if there were any). Some tires turn into iceskates after a surprisingly few heat cycles.

Cords are certainly not good if you're running even moderately hard. Absent cords showing, heat cycles are usually the determining factor regarding grip (or lack thereof) as MS-Mike said.

Mike, How about some examples. Previously I used GY SC3 and found them very consistent over a season. At 10-12 track days and four sessions per day that would be 40-48 heat cycles.

rbpeirce wrote: Mon Aug 19, 2024 7:53 am Mike, How about some examples. Previously I used GY SC3 and found them very consistent over a season. At 10-12 track days and four sessions per day that would be 40-48 heat cycles.

Are you trailering the car to your track days? If not and/or you street drive the car elsewhere on regular streets, then each of those outings will likely count as heat cycles depending on driving variables.

Regular street tires do just fine with lots of heat cycles but aren't as sticky for track use whether new or after significant cycles/wear. Conversely, more dedicated track tires (ie: Hoosier R7 & A7, Dunlop SMR2, MPSC2 or MPSC2-R) are extremely sticky but will be adversely affected in short order by heat cycles. Performance can start to fall off after 3 or 4 full cycles.

Great idea to compare tread wear experiences. There are a lot of variables to be sure: car hp, weight, track type, track temp, driver style, session length or race laps, etc. But it is still a fair question and examples might be interesting. Let me look at my notes to jog my old brain for some of the tires.

I will say that I would be surprised if I got 48 track sessions out of any tire set. Most recently I trashed a new set of BS RE71s in my 135 after two longish autoX (~1.1 mi, 4 sessions), then 6 20-min sessions at Laguna Seca, followed by 4 sessions at Sonoma. The 4th session at Sonoma was useless, so I swapped the street wheels for the 5th (Mich Pilot Super Sports).

I tow a motorcycle with the car track wheels and ride the bike between car sessions.

I may be easier on tires because at my age I don't push as hard as I used to. I usually figure I'm 3-5% off the best times others are achieving. That gives me reasonable times, just not the best. It likely also gives me better tire wear. I try to get thru a 10-12 track day season on one set. The GYs could do that. I'm not so sure about the Nankangs.