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Do I need to chuck these MPSC2s just because of this one tread block?
My front MPSC2s have spent 2 days at Thunderbolt - a total of nine 23-minute sessions. Overall the tread looks good, except for the block just inside the outside shoulder, which has worn at an angle all the way down to the wear bar. The left tire is worse than the right (CW track), but they're both pretty worn in the same way. Are these done? And if so, WTF, Michelin? Or, more probably, WTF am I doing to cause this? Note the rear tire in the background of the first pic - totally fine.
Very common wear pattern. I used to get 16 to 20 heat cycles with them although they lacked grip by then. Take a look at the 981 GT4 sub forum, also 718 GT4, lots of discussion on tire wear and understeer.
Very common wear pattern. I used to get 16 to 20 heat cycles with them although they lacked grip by then. Take a look at the 981 GT4 sub forum, also 718 GT4, lots of discussion on tire wear and understeer.
I did a search - not as much as you might think about this particular problem, although there is some talk about it in the GT3 forums.
Do you think I could swap the front tires left/right and get another 9 heat cycles out of them? I'd like them to last more than 2 days...
I did a search - not as much as you might think about this particular problem, although there is some talk about it in the GT3 forums.
Do you think I could swap the front tires left/right and get another 9 heat cycles out of them? I'd like them to last more than 2 days...
Yes on swapping side to side. I used to swap mid way through an event. Lots of variables in projecting tire life but I think you can get more out of those. Of course need to consider how far you have to drive home on them. Generally in my experience it's the outer tread block you need to watch as that area will usually cord first on a GT4. Depends on alignment too- how much neg camber you are set up with.
Edit- for info here is end-of-life on my 981 GT4 for a MPSC2 You can just see the cords showing on the outer edge. I think this was with about neg 2.5 deg camber in front.
That tire looks perfect to me. I can also see how that same tread block on yours is worn down further than the rest of the treads. I'll gamble a bit and run them for one more event, keeping an eye on them. It's a 4 hour drive home from Watkins Glen.
The wear bars don't mean anything for the track, that's just the legal minimum for tread depth on street tires based on some estimate of what's needed for safe traction in the rain. In dry conditions you can run the tires safely well below the wear bars, until the cords start to show. As others have noted, that will typically occur on the outside shoulder of your outside tire.
Tire looks fine. We run cup2s on a GT4 CS MR in endurance racing and have done a 14 hour race on one set of tires, no problem. You might want a bit more camber, we run -3. What tire pressures are you running?
Tire looks fine. We run cup2s on a GT4 CS MR in endurance racing and have done a 14 hour race on one set of tires, no problem. You might want a bit more camber, we run -3. What tire pressures are you running?
Good to hear. Hopefully it won't rain on my drive home!
Re: Pressures - I try to stay in the low 30s. Sometimes in the morning, before I've bled the pressure all the way down (I don't want to start cold in the morning much lower than 29), they can get to about 36 or 37 hot before I come in. But after bleeding more air, subsequent sessions are all about 31F 33R hot.
Re: Camber - I'm trying to stay away from too much more camber because 1) This car is 50/50 street/track and 2) I'm trying to hold off on any extra suspension hardware right now. I'm at -2.4F and -1.9R with just shims.
No sure what marks you mean, Bruce, but either way... no. I don't trailer my car.
OK, thought so.
The lines on the shoulder that look like the beginnings of cording. My trailer sometimes "engraves" those same lines when the tires are hot and I trailer up right when I come off the track.
Basically the lines from the floor and ramps of the trailer.
If you don't trailer, it's irrelevant.
I think you can rotate those tires and you'll be fine for another few days. Check them after every session, and if you start seeing metal, then chuck 'em. Safety first. My .02
The lines on the shoulder that look like the beginnings of cording. My trailer sometimes "engraves" those same lines when the tires are hot and I trailer up right when I come off the track.
Basically the lines from the floor and ramps of the trailer.
If you don't trailer, it's irrelevant.
I think you can rotate those tires and you'll be fine for another few days. Check them after every session, and if you start seeing metal, then chuck 'em. Safety first. My .02
If you start seeing cord chuck them.
If you start seeing metal that means having gone through several layers of cord and is no bueno.
05-06-2021, 08:23 PM
Do I need to chuck these MPSC2s just because of this one tread block?
