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      11-23-2012, 10:44 AM   #1
ERinEC
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Adverse Effects Upsizing Just Rear Tires?

My 2011 E92 has the PS2s in OEM sizes on ZCP wheels. With almost 11,000 miles on my car, the rears are practically shot.

I want to purchase the Michelin Super Sports in 275/35 and keep my front (245/35) tires on for a bit as they're not ready to be replaced. Will I have any issues to speak of with this setup? Once the front tires are ready for replacing, I would size up to 255/35.
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      11-23-2012, 11:11 AM   #2
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In theory you should experience more understeer with wider rears. For normal street driving you should not notice a difference. In theory you could correct the extra understeer by taking camber out of the back with an alignment. (=overkill)

Other than that tire diameter is pretty close to 265 so there shouldn't be any issues.
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      11-23-2012, 11:53 AM   #3
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Quote:
Originally Posted by ERinEC View Post
My 2011 E92 has the PS2s in OEM sizes on ZCP wheels. With almost 11,000 miles on my car, the rears are practically shot.

I want to purchase the Michelin Super Sports in 275/35 and keep my front (245/35) tires on for a bit as they're not ready to be replaced. Will I have any issues to speak of with this setup? Once the front tires are ready for replacing, I would size up to 255/35.
I suggest you contact Ben@tirerack (forum member) because he has stated several times now that Michelin recommends not mixing PSS and PS2 tires.
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      11-23-2012, 12:13 PM   #4
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Originally Posted by M3SQRD View Post
I suggest you contact Ben@tirerack (forum member) because he has stated several times now that Michelin recommends not mixing PSS and PS2 tires.
Interesting- thanks for the heads up, I will definitely reach out to him.
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      11-23-2012, 12:19 PM   #5
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Interesting- thanks for the heads up, I will definitely reach out to him.


Just noticed you live in MD - we might be "neighbors"
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      11-23-2012, 01:52 PM   #6
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Just noticed you live in MD - we might be "neighbors"
Hey there.

It looks as if EC in your location may match the EC in my screen name. Are you in Ellicott City?
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      11-23-2012, 01:54 PM   #7
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Hey there.

It looks as if EC in your location may match the EC in my screen name. Are you in Ellicott City?
EC = East Coast

I'm in Mont Co so I'm ~40 min away from you.
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      11-23-2012, 01:57 PM   #8
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EC = East Coast

I'm in Mont Co so I'm ~40 min away from you.
Aaah, gotcha. I grew up in Rockville/Potomac.

Looks like you've been to a bunch of track events (I viewed some of your earlier posts). I just picked up my M3 about two months ago and look forward to some HPDEs this spring!
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      11-23-2012, 02:06 PM   #9
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Aaah, gotcha. I grew up in Rockville/Potomac.

Looks like you've been to a bunch of track events (I viewed some of your earlier posts). I just picked up my M3 about two months ago and look forward to some HPDEs this spring!
You'll have a blast at the track with your M3! Although Summit Point is conveniently located, a trip to VIR is soooo worth it
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      11-23-2012, 02:13 PM   #10
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You'll have a blast at the track with your M3! Although Summit Point is conveniently located, a trip to VIR is soooo worth it
I took my S4 to VIR a couple years ago with the Audi Club and finally figured out what all the fuss was about! Can't wait to get back there.

I also did an HPDE at Summit Point's Shenandoah Circuit several years ago and enjoyed that too!

With which orgainization do you belong to for track events?
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      11-24-2012, 08:05 AM   #11
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I took my S4 to VIR a couple years ago with the Audi Club and finally figured out what all the fuss was about! Can't wait to get back there.

I also did an HPDE at Summit Point's Shenandoah Circuit several years ago and enjoyed that too!

With which orgainization do you belong to for track events?
VIR is definitely worth the drive down, even in a fixed-back race seat!

I've tracked with pretty much every organization in our area. However, I haven't participated in a SP FATT for over 15 years! SP Seat Time events are a great value.
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      11-25-2012, 04:25 AM   #12
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Quote:
Originally Posted by ERinEC
My 2011 E92 has the PS2s in OEM sizes on ZCP wheels. With almost 11,000 miles on my car, the rears are practically shot.

I want to purchase the Michelin Super Sports in 275/35 and keep my front (245/35) tires on for a bit as they're not ready to be replaced. Will I have any issues to speak of with this setup? Once the front tires are ready for replacing, I would size up to 255/35.
First of all, do not mix PSS and PS2 (or any other brand for that matter), as the different grip and roll characteristics of different front and rear tyres causes an imbalance in handling. I experienced this first hand when I fitted PSS (oem size) to the rear only to see how handling changed.

Upsizing the rears only will have more effects than just increasing the tendency for understeer at the limit; you may also increase oversteer in the wet as the wider rear tyres are more prone to aquaplaning. Not only that, the car will also be raised slightly at the rear due to the increased height of the tyre sidewall, and the roll characteristic of the rear will also be changed due to an increase in rear track width. These changes will undoubtedly affect handling balance. Therefore, if you want to upsize, do it proportionally.

Last edited by mlhj83; 11-25-2012 at 10:55 PM.
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      11-25-2012, 01:33 PM   #13
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Quote:
Originally Posted by mlhj83 View Post
First of all, do not mix PSS and PS2 (or any other brand for that matter), as the different grip and roll characteristics of different front and roll tyres causes an imbalance in handling. I experienced this first hand when I fitted PSS (oem size) to the rear only to see how handling changed.

Upsizing the rears only will have more effects than just increasing the tendency for understeer at the limit; you may also increase oversteer in the wet as the wider rear tyres are more prone to aquaplaning. Not only that, the car will also be raised slightly at the rear due to the increased height of the tyre sidewall, and the roll characteristic of the rear will also be changed due to an increase in rear track width. These changes will undoubtedly affect handling balance. Therefore, if you want to upsize, do it proportionally.
The above poster makes some good points; however in my experience with both tires, the PSS has significantly more grip than the PS2 in the wet making the PSS with full tread depth more grippy and capable in the wet in all conditions than the standard sized PS2 even if upsized to the 275 size. The bigger difference is the large change in traction characteristics from the PSS's new compound and tire construction.

As the previous poster stated, the roll difference is significant. The PS2 does not generate as much lateral grip as the PSS. It will make for a very wonky handling car at the limit. The fronts will not be able to generate enough grip and the car will understeer significantly more than with matched PS2's. I have tried the two different kinds of tires on my own car and found this result. Even with full PSS in stock sizes, the car rolls more with the additional grip (given nothing else in the suspension changed such as camber, spring rates, toe settings-- the whole car has more grip and it takes more throttle to get the rear tires to break traction).

But, like other posters say, if you never track the car or drive with MDM on/DSC off the difference will not be very large.

In principle, though, I would run matching front and rears. Another 11K miles is a long time to drive with mismatched tires. I bought this car for the way the whole package behaves under all conditions and if my car handled funky when pushed hard it would annoy me greatly.

Go full PS2 or full PSS. Both are incredibly good tires (even PS2 still).
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