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      09-09-2018, 06:01 AM   #1
casualDIYer
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Chunked: MPS4S

At a track weekend this September, a less than two month old MPS4S tire chunked. One chunk actually revealed a chord so I guess the life of this tire has come to a very short and unhappy end. I was running 38PSI hot on the tire that died. PSI seemed reasonable but there was no doubt the tire was rolling over itself. I guess a hot temp of 40-42 might have been a better choice despite the greasiness I feel as they warm up after a few laps.

Any suggestions on how to prevent 'chunking' in the future at a track day with these tires??

Thanks.
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      09-09-2018, 06:54 AM   #2
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On which kind of turns was the tire rolling over itself like in an auto-X ? If it was a rather slow very tight bend under hard braking - then sometimes driving style changes ( minus suspension changes ) and of course tire inflation.
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      09-09-2018, 11:35 AM   #3
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Quote:
Originally Posted by menncars View Post
Any suggestions on how to prevent 'chunking' in the future at a track day with these tires??
Have you modified the camber to a more track-friendly setting?

How did you determine that you were running 38 psi hot?

There are quite a few photos across the 'net showing chunked, corded, and otherwise used-up MPSS' after a single track event. The 4S is susceptible to the same issues. Lack of negative camber, too-high or too-low tire pressures, over-driving the car into the corners, and street braking will all contribute to heating the tire to a point where it gives up.

I've come to the conclusion that street tires in this category aren't suitable on race tracks when placed on relatively heavy, high-horsepower cars.
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      09-09-2018, 12:23 PM   #4
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Quote:
Originally Posted by menncars View Post
At a track weekend this September, a less than two month old MPS4S tire chunked. One chunk actually revealed a chord so I guess the life of this tire has come to a very short and unhappy end. I was running 38PSI hot on the tire that died. PSI seemed reasonable but there was no doubt the tire was rolling over itself. I guess a hot temp of 40-42 might have been a better choice despite the greasiness I feel as they warm up after a few laps.

Any suggestions on how to prevent 'chunking' in the future at a track day with these tires??

Thanks.
They are not tires suitable for the track. Sidewalk is very soft. You should run them over 40 psi and also have more camber at least M2 LCAs

Changing your driving style would help, do very late apexes and sharp turns at lower speed instead of plowing into corners

But the real answer is to use a different tire
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      09-09-2018, 01:22 PM   #5
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Extreme performance tires will hold way better for track use.
Or drive at little slower pace at the track.
MP4S can be rolled over badly.

I auto crossed with MPSS and I had to pump up to 48psi hot in front.
Now with RE71r, I can stay at 32psi hot. (or even lower)
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      10-07-2018, 08:33 AM   #6
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Quote:
Originally Posted by menncars View Post
At a track weekend this September, a less than two month old MPS4S tire chunked. One chunk actually revealed a chord so I guess the life of this tire has come to a very short and unhappy end. I was running 38PSI hot on the tire that died. PSI seemed reasonable but there was no doubt the tire was rolling over itself. I guess a hot temp of 40-42 might have been a better choice despite the greasiness I feel as they warm up after a few laps.

Any suggestions on how to prevent 'chunking' in the future at a track day with these tires??

Thanks.
These are not track tires - the sidewalls are too soft - ask me how I know! They are excellent street tires. They are nearly the same as the MPSS tires. Get a set of Hankook R-S4s for the track. They have a very stiff sidewall and hold up extremely well as a track tire.
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      10-09-2018, 02:41 PM   #7
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get a tire made for the track.

re71r's, nt01s, direzzas, etc...
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      10-15-2018, 07:24 PM   #8
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MPS4S are wonderful tires for the street, great grip in the wet and super smooth and quiet. Love em and enjoy the n the street. Get a 17 inch square set up and 225/45/17 Potenza RE71 for the track. They are noisy pick up debris sand like a wheel bearing is going out and sick like glue. MPS4S will help you to enjoy the RE71s and visa versa. you'll need a harbor freight 1.5 ton jack and torque wrench too ..
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