Michellin Supersport PSS correct size

F

FD3S

Member
Hello I would like to ask a quick question. What is the right size for BMW Z4M for Michelin Supersport with standard wheels?
255/40/18
225/45/18

or

255/45/18
225/45/18

???
 
First option is correct - which keeps the front to rear tyre ratio the same despite the wider rear tyre.

If you did the 2nd option, you'd end up with a rear tyre profile that was about 1cm taller than the front:
  • 225/45r18 = 660mm diameter
  • 255/40r18 = 661mm diameter
  • 255/45r18 = 687mm diameter

Another option is a:
  • 265/40r18 = 669mm diameter
...which is what I had fitted as the 255/40 was not available originally, and I just stuck with it - but you may get a slight rubbing on hard compressions (I only get it in 2 places on the 'Ring, but that's with aftermarket suspension on hard settings).
 
Yes, the first option is factory sizes.

But when I bought new tyres in April I went with your 2nd option for a bit more sidewall and haven't had any issues - plus they fill the wheelarches a bit more!
 
I do believe the answer was much closer than this forum; either on the note by your driver door or in the owners manual.
 
Argenta said:
I do believe the answer was much closer than this forum; either on the note by your driver door or in the owners manual.
Click to expand...
Assuming the OP was with the car!

The internet is with you 90% of the time even when you're in another county/country without the car!
 
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