I’m trying to understand what I likely did wrong with my tires.

[2023EGM1]

Hey everyone,

I’m trying to understand what I likely did wrong with my tires.

Car is a Mustang Mach 1 (non-Handling Package) on OEM sizes:
255/40R19 front
275/40R19 rear

Tires are Michelin Pilot Sport 4S.

I did only one track day about 2 years ago, when the tires were around 1 year old. It was my first time on track, and I only did 2 sessions of around 10–15 minutes each.

After that day, all 4 tires ended up looking like this (photos attached): cracked/crazed shoulders and outer tread blocks, almost like the surface got cooked.

Some context:

• Car was basically stock alignment/setup
• I wasn’t very experienced at the time, so likely not smooth with inputs
• I honestly don’t remember hot pressures or whether I bled air between sessions
• This happened on all 4 tires, not just fronts

From what I’ve been reading, this seems like overheating / heat cycling damage rather than just wear, but I’m surprised it happened so fast with so little track time.

Questions:

1. Did I simply overdrive the PS4S beyond its thermal limits?
2. Was this likely pressure related (starting too high / not bleeding hot pressures)?
3. Is this normal-ish for a heavy car like a Mach 1 on PS4S during a beginner track day?
4. For occasional track days, would you stay with PS4S or move to something else?

Would appreciate any feedback so I don’t repeat this with my next set.

Thanks!

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[2023EGM1]

The tires…

 

[Swtbabybilly]

Looks like the tires have dry cracks, from the 1 picture it looks like those tires are from 2022 (atleast the one in the first picture) so they have 4 years of aging on them. Some tires shines also dry out your tires which might explain why its mostly on the edge of the tire that spot is also where the sun beats on the tire so that would speed it up also. So long story short i dont think its something you did going to the track they are just getting old and showing thr age, best of luck

 

[Mike Pfeifer]

Looks like the tires have dry cracks, from the 1 picture it looks like those tires are from 2022 (atleast the one in the first picture) so they have 4 years of aging on them. Some tires shines also dry out your tires which might explain why its mostly on the edge of the tire that spot is also where the sun beats on the tire so that would speed it up also. So long story short i dont think its something you did going to the track they are just getting old and showing thr age, best of luck

Was going to suggest essentially the same thing.

 

[NightmareMoon]

How old were the tires when first tracked? Were they brand new, or have a few years on them?

MP4S really need camber to survive well on track. OEM alignment has very little camber. Theres more, but I need an answer to the above question first.

 

[2023EGM1]

How old were the tires when first tracked? Were they brand new, or have a few years on them?

MP4S really need camber to survive well on track. OEM alignment has very little camber. Theres more, but I need an answer to the above question first.

They were close to 1.5 years, and maybe 3.000 miles. Now they're at 6.000 miles.

 

[NightmareMoon]

They were close to 1.5 years, and maybe 3.000 miles. Now they're at 6.000 miles.

Any cold weather driving? i.e. below 32°? (before or after the event) That can contribute to cracking. Those look like they've been driven in some cold temps to me.

Either way, I think just get some camber plates, go for a more aggressive alignment (front and rear), and you should be fine. Suitable camber and managing your tire pressures will allow the whole tread to work and the shoulders won't take as much of the brunt of it. Then listen to the tires and when they're screaming don't just add more and more steering wheel angle if its not getting a result. Its definitely possible to abuse the tires and make things worse if you don't know yet what you're doing.

If you get new street tires, probably a good idea not to take them straight to the track right after mounting them. Get them some hot cycles and some time to cool inbetween before your first track day (3k miles is is plenty to do that).

MP4S aren't the best track tire for heavy car, but they work for many many people. With camber you should be fine. With OEM camber, you just overheat the edges like that. You don't need a ton, it takes over three degrees front camber to wear tire on track evenly, but OEM is 1.X and ballpark of 2.7 can be enough to manage things. It will still wear the shoulders faster with 2.7 but it won't be nearly as bad.

As you've found out, it really doesn't matter if you get a tiny bit more daily wear from the extra camber if you're tossing the tires out at 6k miles because they're dead from insufficient camber on track. I run over three degrees on the street and still get 20k miles from a set of MP4S. I have dedicated wheels and tires for events though, so my street tires only see street duty.

 

[2023EGM1]

Any cold weather driving? i.e. below 32°? (before or after the event) That can contribute to cracking. Those look like they've been driven in some cold temps to me.

Either way, I think just get some camber plates, go for a more aggressive alignment (front and rear), and you should be fine. Suitable camber and managing your tire pressures will allow the whole tread to work and the shoulders won't take as much of the brunt of it. Then listen to the tires and when they're screaming don't just add more and more steering wheel angle if its not getting a result. Its definitely possible to abuse the tires and make things worse if you don't know yet what you're doing.

If you get new street tires, probably a good idea not to take them straight to the track right after mounting them. Get them some hot cycles and some time to cool inbetween before your first track day (3k miles is is plenty to do that).

MP4S aren't the best track tire for heavy car, but they work for many many people. With camber you should be fine. With OEM camber, you just overheat the edges like that. You don't need a ton, it takes over three degrees front camber to wear tire on track evenly, but OEM is 1.X and ballpark of 2.7 can be enough to manage things. It will still wear the shoulders faster with 2.7 but it won't be nearly as bad.

As you've found out, it really doesn't matter if you get a tiny bit more daily wear from the extra camber if you're tossing the tires out at 6k miles because they're dead from insufficient camber on track. I run over three degrees on the street and still get 20k miles from a set of MP4S. I have dedicated wheels and tires for events though, so my street tires only see street duty.

Thanks very much for your time and advise! Some mornings can get on the low 30s high 20s, but I barely drive this car when cold. I'll get more camber before the next track day, I don't go too often.

Should I keep these tires to finish them at the track or they have no use whatsoever?

 

[NightmareMoon]

Thanks very much for your time and advise! Some mornings can get on the low 30s high 20s, but I barely drive this car when cold. I'll get more camber before the next track day, I don't go too often.

Should I keep these tires to finish them at the track or they have no use whatsoever?

Last thing you want is a tire to fail on track. I certainly wouldn't keep them for that.

Most summer tires aren't supposed to be driven below 32 (and cracking is the result). Some can take it, so you'll have to do some research and track down manufacturer specs. Yokohama A052 (for example) is good to a lower temp. If you plan on continuing to drive occasionally in high 20s, I'd start looking for a different summer tire or a good all-season.

 

[2023EGM1]

Makes sense... thanks again!

 

[GTP]

The shoulders show that neither low air pressure nor insufficient camber caused this. Otherwise the scrub area would reach farther down to the sidewall.

At Pitt Race a couple years ago, the track surface was so abrasive that I corded all 8 shoulders of the tires in a single weekend. And I had proper alignment & camber, etc.

@2023EGM1 what track was this?

 

[2023EGM1]

It's a local track down in south america.

 

[GTP]

Maybe ask around to see if others think the surface is abrasive and what is their experience with tire wear?

Do you want to track more often?

 

[tom_sprecher]

Don't know what to tell you. The Michelin Pilot Sport 4S has a TWR of 300, so they're kinda hard to begin with. They had a year of driving on them, so they were full tread and sat out in the UV cross linking the whole time.

I don't have any experience with a tire on track that wasn't shaved and had a TWR of 100. Get some Toyo R888R's, and bag and garage them when not in use.

 

[Anyone3505]

Last thing you want is a tire to fail on track. I certainly wouldn't keep them for that.

Most summer tires aren't supposed to be driven below 32 (and cracking is the result). Some can take it, so you'll have to do some research and track down manufacturer specs. Yokohama A052 (for example) is good to a lower temp. If you plan on continuing to drive occasionally in high 20s, I'd start looking for a different summer tire or a good all-season.

Many MFGs put their summer tire temp threshold in the mid-40s:
Continental- https://www.continental-tires.com/tire-knowledge/summer-or-winter-tires/
Michelin, however, isn't as firm in their summer tire temperature guide: "Designed for warm, dry, or wet roads. Provide excellent cornering and braking above 45°F. Unsafe on snow and ice; rubber hardens in cold temperatures." https://www.michelinman.com/auto/au...e-buying-guide/summer-winter-all-season-tires

Tire Rack- https://www.tirerack.com/upgrade-garage/can-i-drive-summer-performance-tires-in-cold-temperatures

I know many people using winter tires in the bumper months and have no concerns, but i feel differently.

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