So....been thinking alot about the straight line traction on the M3 and wanted to posit a "theory thread" on what BMW and Michelin did to tweak this tire.
Let's establish a few background items to agree upon:
1. This is not the highest powered, highest torque RWD sedan or coupe on the planet made in the last decade.
2. Michelin PSS, historically, is one of the absolute best street tires for traction
3. The M seems to suffer more tire slip from a straight line acceleration standpoint than most historical comparatives, despite having some of the most advanced tire compound, suspension, and differential technology available.
Now....here are a few observations:
1. I owned Michelin PSS on my e39 m5 in 245/40/18 and 275/35/18 tire sizing. These tires have a more rounded shoulder profile....I think there is less contact patch pressure on the shoulders of these tires than the standard michelin PSS. This may be for wet traction or for handling purposes. This is based upon eyesight alone - I literally can see that these tires fall away more from than mid-point than my past experience with this tire.
2. These appear to be very slow wearing, even by PSS standards. Member Suave, rocking 19's and having done a good amount of track time in Europe, has 5k miles on his. I just checked them out and I think he'll get 15k out of them. Easy. On the rear with 19" wheels.
Member Karussell has done a ton of track time on his 18s, including lots of drifting, and was reporting barely visible wear (i.e. it was visible, but not by much) at 6k miles.
3. The M3 may have straight line traction problems but it's cornering prowess is amazing. Look at the reviews from modified e9x owners running similar tires who have tracked the f80/f82 stock....now the suspension tech and diff are new, and the chassis is lighter, but perhaps the PSS have been optimized for lateral traction at the expense of some straight line capability?
4. Owners, including me, have commented that these tires appear a bit louder than regular Michelin PSS. This is confounded by the solid mounted rear diff and obviously different platform, but it's a pretty consistent theme.
5. BMW/Michelin have said that they changed the contact patch shape of the tires, even front to back, in order to benefit things like steering and slip angle traction. I believe they elongated the contact patch in the front (which might be why I can visibly see a height difference from center to shoulder)
So here goes my theory:
I think the M-specific Michelin PSS had their compounds tweaked to provide longer life, greater lateral traction, possibly slightly improved wet traction (or hydroplaning resistance possibly), and took a slight penalty in noise and a penalty in straight line traction.
Therefore if you go back to regular PSS, my theory would be those would be the things you are giving up....as well as possibly some unique tuning related to the chassis and suspension and steering feel and performance.
I'm over-caffeinated and needing a distraction, so I'm giving theories here. :)
Let's establish a few background items to agree upon:
1. This is not the highest powered, highest torque RWD sedan or coupe on the planet made in the last decade.
2. Michelin PSS, historically, is one of the absolute best street tires for traction
3. The M seems to suffer more tire slip from a straight line acceleration standpoint than most historical comparatives, despite having some of the most advanced tire compound, suspension, and differential technology available.
Now....here are a few observations:
1. I owned Michelin PSS on my e39 m5 in 245/40/18 and 275/35/18 tire sizing. These tires have a more rounded shoulder profile....I think there is less contact patch pressure on the shoulders of these tires than the standard michelin PSS. This may be for wet traction or for handling purposes. This is based upon eyesight alone - I literally can see that these tires fall away more from than mid-point than my past experience with this tire.
2. These appear to be very slow wearing, even by PSS standards. Member Suave, rocking 19's and having done a good amount of track time in Europe, has 5k miles on his. I just checked them out and I think he'll get 15k out of them. Easy. On the rear with 19" wheels.
Member Karussell has done a ton of track time on his 18s, including lots of drifting, and was reporting barely visible wear (i.e. it was visible, but not by much) at 6k miles.
3. The M3 may have straight line traction problems but it's cornering prowess is amazing. Look at the reviews from modified e9x owners running similar tires who have tracked the f80/f82 stock....now the suspension tech and diff are new, and the chassis is lighter, but perhaps the PSS have been optimized for lateral traction at the expense of some straight line capability?
4. Owners, including me, have commented that these tires appear a bit louder than regular Michelin PSS. This is confounded by the solid mounted rear diff and obviously different platform, but it's a pretty consistent theme.
5. BMW/Michelin have said that they changed the contact patch shape of the tires, even front to back, in order to benefit things like steering and slip angle traction. I believe they elongated the contact patch in the front (which might be why I can visibly see a height difference from center to shoulder)
So here goes my theory:
I think the M-specific Michelin PSS had their compounds tweaked to provide longer life, greater lateral traction, possibly slightly improved wet traction (or hydroplaning resistance possibly), and took a slight penalty in noise and a penalty in straight line traction.
Therefore if you go back to regular PSS, my theory would be those would be the things you are giving up....as well as possibly some unique tuning related to the chassis and suspension and steering feel and performance.
I'm over-caffeinated and needing a distraction, so I'm giving theories here. :)
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