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      07-18-2013, 10:47 PM   #1
The_Ring_Monster
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235/265 Michelin PSS + stock setup

Hi All,

I need some help from all you wheel / suspension gurus. I've been doing some extensive research to replace my stock OEM tires. Everything on the car is stock suspension and wheel wise. I'm looking to purchase a set of Michelin pilot super sport tires for improved handling and grip. The car will be 80% street use and 20% track and autox.

What do you guys think about the following tire size? Would I need any adjustments or mods to make them fit?

Front: PSS 235/40/18
Back: PSS 265/35/18

Any tips and guidance will be greatly appreciated, thanks!
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      07-18-2013, 11:11 PM   #2
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thats ideal setup for stock wheels
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      07-18-2013, 11:34 PM   #3
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I understand this has been done on stock wheels and suspension with no rubs:

Front: PSS 245/40/18
Back: PSS 275/35/18

What I plan to run on my next set, so you should have margin.
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      07-18-2013, 11:50 PM   #4
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a few people have run 245/275 on stock wheels on the forum. that being said i have a pair of 245/40/18 michelin pss's if anyone in cali needs them haha
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      07-18-2013, 11:56 PM   #5
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Just checked my fronts. Have another 8-12 months of tread left.

Seriously? New or used?
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      07-19-2013, 12:33 AM   #6
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yes serious, they are used, much less than 4k miles on them.
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      07-19-2013, 09:29 AM   #7
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Quote:
Originally Posted by The_Ring_Monster View Post
The car will be 80% street use and 20% track and autox.
[...]
Front: PSS 235/40/18
Back: PSS 265/35/18
You may also want to consider:
Front: 235/45/18
Rear: 265/40/18
This setup fits fine and, compared to the one you mentioned, it has two main advantages:
- the overall wheel diameter is closer to the original one, and actually improves speedometer precision;
- the sidewall is just a tad higher than original, which offers better rim protection.
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      07-19-2013, 11:49 AM   #8
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Quote:
Originally Posted by RobertRO View Post
You may also want to consider:
Front: 235/45/18
Rear: 265/40/18
This setup fits fine and, compared to the one you mentioned, it has two main advantages:
- the overall wheel diameter is closer to the original one, and actually improves speedometer precision;
- the sidewall is just a tad higher than original, which offers better rim protection.
Thanks for this! You mentioned that the thicker sidewall will improve speedometer precision, now I'm curious to find out how the 235/40 265/35 will affect speedometer readings. Any idea?
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      07-19-2013, 12:00 PM   #9
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235/265 is ideal for OEM widths.

Going 245/275 isn't recommended by me because it will result in tire shimmy on the wheel, which will reduce overall grip and response of the tire.

I run 235/45 and 265/40
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      07-19-2013, 12:44 PM   #10
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Quote:
Originally Posted by Kgolf31 View Post
235/265 is ideal for OEM widths.

Going 245/275 isn't recommended by me because it will result in tire shimmy on the wheel, which will reduce overall grip and response of the tire.

I run 235/45 and 265/40
can you elaborate on how a 245 will cause tire shimmy?
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      07-19-2013, 01:34 PM   #11
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Quote:
Originally Posted by dorifto88 View Post
can you elaborate on how a 245 will cause tire shimmy?
You're fitting too much tire on a limited width wheel.

Can you fit 245s on the wheel? Of course. Is it beneficial? Nope.

There comes the law of diminishing returns when it comes to tire size on a confined wheel width. 245 is that limit.

When you get a tire on a wheel that much, the tire actually moves back and forth on the wheel before the sidewall deflects and you get your grip.

From the time the tire moves, to when the sidewall actually deflects takes away response and actual corner grip from the wheel.


This is why you don't see many people squeezing street tires as big as they can onto a wheel when it comes to competition. They can probably go +20mm bigger, but it isn't ideal. For example, on a 9.5" wheel I'd go 265mm. Even though you could go up to 285mm most likely, stretching the sidewall a bit to make it stiffer increases response and feel through the wheel.


Now, when you get to R-Comps...this is a different story.

And when you're really pushing the tire, this is what deflection looks like:

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      07-19-2013, 02:49 PM   #12
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Man, this is a timely thread! I'm planning on the same PSS setup and was wondering what other people think. I was wondering about 235/40 or 235/45 and 265/35 or 265/40.
What are the advantages of going with 235/40 and 265/35? I'm looking to purchase in the next few weeks.
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      07-19-2013, 03:15 PM   #13
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235/40 and 265/35 provide a bit more wheel torque (smaller diameter), a bit more sidewall stiffness, and a small bit of ride penalty (but with the softer PSS sidewall, it's largely negated vs. say a very stiff sidewall tire).

BTW, the right sizes are 235/40 (not 45) and 265/35. I really like this combo on stock wheels. A lot!

Kgolf's explanation is on the money. On the track, I tried running the 245/275 combo on stock wheels. Despite attempts to adjust tire pressure, the center of the tire was consistently 20 degrees or so hotter than the inside or outside edges. That means all that nice extra rubber I bought was going to waste. Traction was horrible, as essentially the middle not the whole tire was providing the contact patch. (A really stiff and square tire, like the old Star Spec, might do better, but I have no data.) Basically it's stuffing too much tire on the wheel. It fits, but if the point is better performance, it doesn't provide it.

We put those same tires on an 8.5/9.5" wheel set and the difference is night and day.
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      07-20-2013, 08:12 AM   #14
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Thanks to OP for starting this thread and thanks Finnegan and Kgolf31. Looks like I'll be going 235/40 and 265/35.
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      08-12-2013, 03:15 PM   #15
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Having now more than one year return of experience on Michelin PSS 19" 235/35 in the front and 265/30 in the rear....I can just encourage you to go for this set which provides a great handling and precision on track.

Don't know how far your size in 18" will make a lot of difference....
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      08-20-2013, 09:09 PM   #16
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Thanks for the valuable feedback guys! I ended up going with the 235/40 and 265/35 setup and it handles like a dream! Now the car feels more alive and ready to pounce, I'm completely satisfied! I haven't gotten the chance to push them hard to the limit yet, but the grip is noticeably improved from what I've experienced so far.
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      08-20-2013, 10:00 PM   #17
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Quote:
Originally Posted by The_Ring_Monster View Post
Thanks for the valuable feedback guys! I ended up going with the 235/40 and 265/35 setup and it handles like a dream! Now the car feels more alive and ready to pounce, I'm completely satisfied! I haven't gotten the chance to push them hard to the limit yet, but the grip is noticeably improved from what I've experienced so far.
Excellent!
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      08-20-2013, 10:08 PM   #18
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With the setup in the original post (Front: 235/40/18 - Back: 265/35/18) on stock wheels, you can also put a 10mm spacer in the rear with no issues.
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      08-22-2013, 09:31 PM   #19
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Quote:
Originally Posted by Shipkiller View Post
With the setup in the original post (Front: 235/40/18 - Back: 265/35/18) on stock wheels, you can also put a 10mm spacer in the rear with no issues.
Ship.... you recomend 10mm spacers in the back for looks? or are there any other benefits?



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      08-22-2013, 10:08 PM   #20
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I put a spacer in the rear to widen the track for straight line braking stability. I put a spacer on the front for handling. Pushing the fronts out makes the car rotate more/reduces understeer. On shorter tracks, slower tracks, I remove the rear spacers.

Of course widening the rear reduces the effect you get when you widen the front. Everything is a trade off...

I learned of this from James Clay of Bimmerworld.

I am contemplating a new set of wheels, going from a 8" to 8.5 (fronts), with an ET of 35 all around. This will push the front wheel out 13mm from stock.
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      10-14-2014, 05:46 PM   #21
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Has anyone run 235/45 fronts and 265/40 rears on stock Z4M OEM wheels (18's with 8" fronts and 9" rears)? I am looking for a little more sidewall height to protect alloy rims from Virginia pot holes (my technician recommended this), and I want to make sure there are NO rub issues before I order them. I can't afford the expense right now or new rims, so that option is off the table. Thanks

Yesterday at 1:14pm · Like
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      04-10-2021, 02:24 PM   #22
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Last edited by sknobs; 04-10-2021 at 02:30 PM..
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