[dpevans]

Learning lessons the hard way, yesterday went off track damaged a rocker so minor damage so it will be an easy fix. I reviewed the video and keep in mind I am not pushing the car to it's limit and have no desire to push it that hard. At Gingerman I'll run 1:48 all day and throw in the occasional 1:45-46. At Mid Ohio I'll run 1:44s so I am not pushing the car that hard, after looking at the video I'm coming out of turn 9 at 85 and the back end comes around and I had no feeling what's so ever it was loosing grip, the car felt well balanced the prior laps running -2.5/-1.5 camber and turning in well, it was the second session and 5th lap and the tire monitor had the tires as warm. When I got back in I check all the corners if something broke and I notice the back tires felt hard not sticky soft like normal and I thought it might have been from driving through the grass. This is my second year on that set of rear tires and the 8th track day with probably 45 sessions and I started autoX this year and have 12 session though they never get over 110 degrees in autoX. I have a new set ready to put on but what is your guys experience on how many heat cycles before you change out and what is a heat cycle, one day or one session.

[Baddawg53]

A heat cycle is a session, every time you go out.

I am not going to say the SC3 won't heat cycle out, but I remember wearing them out before they'd get cycled out. I think if you have any question in the quality of the tire and you know they've got some time on them, then maybe a new set is in order. My last set of Hoosiers were definitely falling off fast around 18-20 heat cycles, and my current set has 9 and I already started to get some push. You can drive them to the cords knowing they aren't as grippy or change them, it's really what your goals are. I change them early usually.

The tires could have been cycled, or someone in front of you could have dropped a little fluid. There's some corners that you go into having complete confidence in the grip, but mentally I try to always think, on every corner, that the car may lose grip and try to feel for that little slide starting to happen. If you went through some fluid it's highly unlikely you were gonna save it, snap oversteer will definitely surprise you.

[TransamGTA350]

SC3's are definitely less sensitive to heat cycling than something like an RE71RS, Cup2 or Hoosier. Like Baddawg53 said, I wouldn't say they won't cycle out before they cord, but they they don't seem to fall off that hard.

I am running RE71RS's this year on a 2nd set of wheels, but I still have a set of SC3's on the stock wheels that have life and I am running them at some HPDE events until they cord (not going to throw away a good set of tires). These SC3's are on their 2nd season, 7 track days, 2 autocrosses, a little more than 1/2 worn and I haven't noticed them falling off in grip, as long as they are fully warmed up.

What I will say is that they do need a lot of heat in them to wake them up. The SC3's can be a little sketchy on a cold morning and because the car is a lot harder on the front tires, the fronts will come up to temperature before the rears and the car will get really loose in the rear for a couple of laps until the rears get hot. I went off in the grass at VIR at turn 4a/4b earlier this year on a cold morning because I didn't recognize that the rears were still cold. No damage or anything, got lucky.

You said this happened on the 2nd session. Did you go back out for later sessions that day and if so, how were the tires then?

[N Camarolina]

I'll add in my datapoint on the SC3s.

I managed to get about 26 track days out of the first set before replacing them, and more for reason of grip than remaining tread (I think I still had about 2-3 32nds left). That might the record for longevity on this forum, and granted these were from my first days in HPDE (starting in Novice) so wasn't pushing the car quite as hard as I drive it now. But in the final 6 or so of those track days, the tires seemed to be down on grip, with corner speeds falling by a couple mph. That's a lot of track days and a lot of heat cycles (typically 3-4 per track day), so I was assuming the rubber was getting harder. The switch to new SC3s made a noticeable improvement.

[dpevans]

Originally Posted by TransamGTA350

SC3's are definitely less sensitive to heat cycling than something like an RE71RS, Cup2 or Hoosier. Like Baddawg53 said, I wouldn't say they won't cycle out before they cord, but they they don't seem to fall off that hard.

I am running RE71RS's this year on a 2nd set of wheels, but I still have a set of SC3's on the stock wheels that have life and I am running them at some HPDE events until they cord (not going to throw away a good set of tires). These SC3's are on their 2nd season, 7 track days, 2 autocrosses, a little more than 1/2 worn and I haven't noticed them falling off in grip, as long as they are fully warmed up.

What I will say is that they do need a lot of heat in them to wake them up. The SC3's can be a little sketchy on a cold morning and because the car is a lot harder on the front tires, the fronts will come up to temperature before the rears and the car will get really loose in the rear for a couple of laps until the rears get hot. I went off in the grass at VIR at turn 4a/4b earlier this year on a cold morning because I didn't recognize that the rears were still cold. No damage or anything, got lucky.

You said this happened on the 2nd session. Did you go back out for later sessions that day and if so, how were the tires then?

It was mid 60s and warming up and normally don't check tire temps the first session. I brought the pyrometer with me to do some hot checks but never got the chance. I'm checking tire temps to monitor camber and air pressure because it was my first day with camber plates. In car tire monitor went from cool to warm by the third lap. the car wasn't in shape for more session after sliding through the sand trap but after checking all four corners nothing was broke so i was able to drive home. Once I got on the road started losing air pressure on the RR and realized the bead was broke but there is a shop just a few miles from the track and the guy slipped me in between his other work. I noticed the backs were not as gummy as the fronts, this is the second set of fronts and original backs. After a session I'm setting air pressures and checking the side walls marks so I am pretty in tune with the condition of the tires.

[TransamGTA350]

Originally Posted by dpevans

It was mid 60s and warming up and normally don't check tire temps the first session. I brought the pyrometer with me to do some hot checks but never got the chance. I'm checking tire temps to monitor camber and air pressure because it was my first day with camber plates. In car tire monitor went from cool to warm by the third lap. the car wasn't in shape for more session after sliding through the sand trap but after checking all four corners nothing was broke so i was able to drive home. Once I got on the road started losing air pressure on the RR and realized the bead was broke but there is a shop just a few miles from the track and the guy slipped me in between his other work. I noticed the backs were not as gummy as the fronts, this is the second set of fronts and original backs. After a session I'm setting air pressures and checking the side walls marks so I am pretty in tune with the condition of the tires.

Might be some clues here. Newer tires on the front vs. rear could definitely result in the rears starting to lose grip sooner than the fronts due to age/heat cycles. If all 4 tires were the same age, they would reduce grip over time more evenly and the handling dynamics would stay the same, just overall be a little slower.

You also said you added camber plates before this track day. I assume that also means you added additional negative camber in the front. Did you also increase negative camber in the rear? What were your previous alignment settings?

[cdrptrks]

In my experience SC3s don't heat cycle out noticeably although they might be a little faster when newer (but the outer half of the tread is not molded to full depth so that gives you a little more contact patch as the tire wears to counteract any slight grip decrease).

By the 5th lap you might be starting to overheat the tires if you're trying to maintain a fast enough pace. A cooldown lap or two with minimal braking can help. If you have PDR, you can open the video file in the free Cosworth Toolbox program on your computer and see the max/min tire temperatures and pressures on each lap. I aim for 34-35 hot personally and tend to feel decreased grip at 37psi and higher but some of that might just be from increasing tire temperature rather than strictly pressure increasing.

I did have one set of 6 year old SC3 takeoffs that had a measurable amount of slightly decreased grip...I'm guessing they might have been exposed to relatively cold weather before I got them but they didn't have or develop any cracks. They still worked for track use but they were more prone to sliding and lap times were a few seconds slower than I expected based on previous SC3s.

[htron435]

IMHO I believe the issue is not the tire wear/heat cycles but the new setup with the camber plates. In adding more negative camber, you’ve added more bite to the front of the car, which naturally will make the rear of the car more prone to oversteer. So at the turn in point the nose of the car grabs sooner — weight transfers more quickly to the front tires and away from the rear tires, which in turn will cause the rear to have less traction than it would’ve previously. To compensate, you’ll learn to be slightly gentler on the steering wheel and on the throttle pedal. Minute changes in steering, braking and throttle inputs will ultimately help you take advantage of the new setup. Hope that helps.

[TransamGTA350]

Originally Posted by htron435

IMHO I believe the issue is not the tire wear/heat cycles but the new setup with the camber plates. In adding more negative camber, you’ve added more bite to the front of the car, which naturally will make the rear of the car more prone to oversteer. So at the turn in point the nose of the car grabs sooner — weight transfers more quickly to the front tires and away from the rear tires, which in turn will cause the rear to have less traction than it would’ve previously. To compensate, you’ll learn to be slightly gentler on the steering wheel and on the throttle pedal. Minute changes in steering, braking and throttle inputs will ultimately help you take advantage of the new setup. Hope that helps.

Adjustment of camber could have a lot to do with it. Would be good to know what the OP is running for front/rear camber.

[dpevans]

Originally Posted by TransamGTA350

Adjustment of camber could have a lot to do with it. Would be good to know what the OP is running for front/rear camber.

-2.5/-1.7 Ran MidOhio with new tires and stuck well. Turn in is amazing. I haven't gone up to -3.0 or more yet.

[TransamGTA350]

Originally Posted by dpevans

-2.5/-1.7 Ran MidOhio with new tires and stuck well. Turn in is amazing. I haven't gone up to -3.0 or more yet.

Shouldn't have any handling/balance issues with those camber numbers, but you'll probably find that you're wearing the outside edge. Something around a -3.0F/-2.0R will help with tire wear.

Sounds like the new tires helped a lot. Assuming they are new SC3's?

[dpevans]

Originally Posted by TransamGTA350

Shouldn't have any handling/balance issues with those camber numbers, but you'll probably find that you're wearing the outside edge. Something around a -3.0F/-2.0R will help with tire wear.

Sounds like the new tires helped a lot. Assuming they are new SC3's?

Yes, I thought getting into those camber numbers is for lower tread wear like 3Rs,

[TransamGTA350]

Originally Posted by dpevans

Yes, I thought getting into those camber numbers is for lower tread wear like 3Rs,

Most 200 treadwear tires seem to like around -3.0F camber, for an advanced level driver. For an intermediate level driver, then the -2.5F you have now is probably good. Rear camber works well at about 0.8-1.0 less than front.

I'm running -2.9F/-2.0R and just finished off a set of RE71RS's. The wear was relatively even, but the outside edge did cord. I'm probably going to change the camber to -3.2F/-2.3R.