Tire pressure for the Cup2 tire at the track??
#46
Rennlist Member
Both the MPSC2 N2 and Dunlop Sport Maxx 2 are game changers.
Really hope that I can make either last 4 track days at Sebring, so I don’t have to screw around with another set of 19” wheels and take off slicks that also only last 2 days.
I did 4 days at the Ring on Dunlops. Although faster and pretty good in the rain (Drove on the same 4 day old tires in heavy, heavy rain today from the Ring to Manchester UK today, up to 70MPH OK in deeper water and without the risk of aquaplaning they were fine to 100MPH) I do like the feel of the Michelin’s better. The Dunlops feel like they are graining, make a bit of rumbling noise and give early warnings but they hang on better = faster.
But the Michelin’s feel more precise but give less warning when they let go..
Im happy with whatever lasts longest.
Both can be run a little higher PSI hot. Say 30-32F en 32-34R
Really hope that I can make either last 4 track days at Sebring, so I don’t have to screw around with another set of 19” wheels and take off slicks that also only last 2 days.
I did 4 days at the Ring on Dunlops. Although faster and pretty good in the rain (Drove on the same 4 day old tires in heavy, heavy rain today from the Ring to Manchester UK today, up to 70MPH OK in deeper water and without the risk of aquaplaning they were fine to 100MPH) I do like the feel of the Michelin’s better. The Dunlops feel like they are graining, make a bit of rumbling noise and give early warnings but they hang on better = faster.
But the Michelin’s feel more precise but give less warning when they let go..
Im happy with whatever lasts longest.
Both can be run a little higher PSI hot. Say 30-32F en 32-34R
#47
I think you could build a quick jack system on the floor of a trailer, or just pull them off the trailer, set them up in a few minutes. hook up the hydraulic ram quick connects and boom, you have a drive over, quick jack, and tires off the ground, Quick jack can run off a battery or generator I believe.
#48
Advanced
I totally get it, and I feel your pain. You would have to commit to jacks, stands, and a generator. to run them. Plus, towing your car. I know you can rent the power at most larger tracks, some have it some don't. I guess for those who already have the trailer and stands, its really not a big deal. Even when you have cold tires, the proper pressure preset when hot will bring that tire back to the correct or close to correct pressure. Then you add or take out if needed
So this is my suggestion
1. Set the tires at normal road pressure. Run your first 3 to 4 laps a moderate speeds, then gradually bring your speed up for your first session, check pressure and tire temp asap. Then make adjustments. I would bet that your ambient temp to "HOT" temp would be much closer to proper race temp without dropping a lot of pressure to start. You really want to get the correct temp, then adjust. I would bet the HOT temp is really way over the proper temp, when you go out on a 24lb tire. Its cooking that tire. Lower pressure heats the tire quickly, the heat continues to build, the heat is causing the increase in pressure. Higher pressure, slower heat exchange, but tire will react properly if you keep the heat within the operating ranges.
i know this is winded and I am rambling over this, but Its really the #1 problem if you plan on getting multiple days out of tires, and consistent tire performance. Also you cannot put warmers on tires sitting on the ground.
So this is my suggestion
1. Set the tires at normal road pressure. Run your first 3 to 4 laps a moderate speeds, then gradually bring your speed up for your first session, check pressure and tire temp asap. Then make adjustments. I would bet that your ambient temp to "HOT" temp would be much closer to proper race temp without dropping a lot of pressure to start. You really want to get the correct temp, then adjust. I would bet the HOT temp is really way over the proper temp, when you go out on a 24lb tire. Its cooking that tire. Lower pressure heats the tire quickly, the heat continues to build, the heat is causing the increase in pressure. Higher pressure, slower heat exchange, but tire will react properly if you keep the heat within the operating ranges.
i know this is winded and I am rambling over this, but Its really the #1 problem if you plan on getting multiple days out of tires, and consistent tire performance. Also you cannot put warmers on tires sitting on the ground.
#50
Most advice I've read has been to avoid IR thermometers and use a tire pyrometer with a probe. IR thermometers can be inaccurate for this application.
#51
Advanced
Good point, I guess a probe is the way to go to get a carcass reading rather than surface. In theory, shouldn't IR be able to penetrate a few mm into the tread to get an internal reading? I guess the thermometer would have to be properly calibrated, to do so.
#53
A lot of good info here. On the gt2rs, start at 26psi on all four? Question I have is at temp, 2-3 laps in, should we try and achieve equal psi front to back? What is ideal psi, at temp, stock gt2rs for front and back?
Also, when to get worried on the track? McLaren is very sensitive to differences between tires but a psi or so should be fine, no?
Ty for the advice
Also, when to get worried on the track? McLaren is very sensitive to differences between tires but a psi or so should be fine, no?
Ty for the advice
#54
I think that's too low to run on a Cup 2 cold. It's not really a dedicated R spec and I'd worry about the side wall of the tyre at low pressures before the car got heat in them, I'd start at 28-29 and bleed down after the first session, but that's just me.
#55
Racer
I've run 26 cold on SP2s in my GT3 in the first session of the day (70-80F). It's just a bit too low, takes most of the first 25min session to get them up to spec.
I too would suggest 28ish on the first session then drop some on the first break. I aim to run 33/35 hot.
Also have side muffler delete for context.
I too would suggest 28ish on the first session then drop some on the first break. I aim to run 33/35 hot.
Also have side muffler delete for context.
#56
Colder starting pressure gets hotter sooner. So if you are too low to start and too low when getting off the track you not getting up to speed to get the tire to perform properly. Its not the pressure at that point, its the speed you are traveling. this is kinda the never ending thread of understanding. extreme low pressure will bake the tire, it will become greasy and stop shedding. I would try your street pressure and see how little they rise, then you may be able to understand the change in pressure is related to heat. In this circumstance, the tire would barely raise.
#58
Rennlist Member
If you are not getting enough heat into the tire, it will be slippery and tear, no Shed, Tear. Tearing looks like ripples of rubber pushed over. Like a paper cut on your finger. They are cold tears. The car will feel like it steps out, then usually catches. Contact temp is not internal temp. So you could go out and spin tires all day long, its not core tire temp. you need core tire temp to really manage this.
I’ll just lower to 30-32 cold and adjust after 4 laps of warm up but sounds like I shouldn’t mess with them after that.
should I get the mpsc2’s with the built in temp sensors? Anyone have some luck with those.
im headed to Laguna Seca in June. Appreciate advice on the track and tire temps. Will be my 4th time there.
hell I might just run my PS4S tires instead
#59
So I think I had this at Thunderhill on This past Saturday. I noticed I had a band of rubber about 2/3 towards the outer edges of the rear tires. Is that a cold tear? I started in the 26/28psi cold and bled them down each time coming off track but each session they got greasy earlier and earlier. by session 4 and 5 the tires were just sliding after half a hot lap. That was their 5th track day. Temp was in mid to high 80’s. So I guess I’m buying new set. Expensive lesson to learn.
I’ll just lower to 30-32 cold and adjust after 4 laps of warm up but sounds like I shouldn’t mess with them after that.
should I get the mpsc2’s with the built in temp sensors? Anyone have some luck with those.
im headed to Laguna Seca in June. Appreciate advice on the track and tire temps. Will be my 4th time there.
hell I might just run my PS4S tires instead
I’ll just lower to 30-32 cold and adjust after 4 laps of warm up but sounds like I shouldn’t mess with them after that.
should I get the mpsc2’s with the built in temp sensors? Anyone have some luck with those.
im headed to Laguna Seca in June. Appreciate advice on the track and tire temps. Will be my 4th time there.
hell I might just run my PS4S tires instead
so lets play a game, if you go faster during the day, you add pressure or remove pressure? This is what tire warmers are for. you heat them up, set pressure. The temp is to the optimal tire temp, or opperating temp. not too hot, not too cold. If you came off the track, and the tire is way higher than the warms, you need to aid pressure to regulate temp, if you are lower than the warms, you would remove pressure. So its simple to start at base temp.
No warmers, set to ambient temp recomended for tire, cup2 has a recomended track setting, then check the pressure and tire temp as soon as you get off the track, if you temp is higher than recomendation, add pressure, if lower, lower pressure, if perfect, dont touch it. As you get faster, you add pressure.