Do M tyres fit on a Z4si ?

Z

zeddy

Member
Z4M roadster specs say 225/45 ZR 18/255/40 ZR 18

Z4 si roadster specs say 225/40 255/35 R18


I'm not really what these codes mean, and I was hoping to put the tyres from the M on to the si. Are the profiles too different?
 
The 18" M rims are wider than the 3.0si 18" rims. Unless you plan to swap wheels too, I would stick with the si specs as there will be no advantage to the M spec tire size.

The number before the slash is the tire width. The number after the slash is the aspect ratio (the ratio of the sidewall height to tread width), and the last number is the wheel diameter in inches. The R after the diameter stands for radial and the letter before the R is the speed rating (the higher the better). http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=46
 
I just realised I had 225 instead of a 255 and have updated the post.

I'm selling an si and was hoping to put the stock tyres from the M on to the si and get some nicer tyres for the M.
 
Z4M roadster specs say 225/45 ZR 18/255/40 ZR 18

Z4 si roadster specs say 225/40 255/35 R18

if the above are correct which I know the SI's are then NO as the rolling circumference will be wrong.
 
srhutch said:
Z4M roadster specs say 225/45 ZR 18/255/40 ZR 18

Z4 si roadster specs say 225/40 255/35 R18

if the above are correct which I know the SI's are then NO as the rolling circumference will be wrong.
Click to expand...
Exactly...as the si is 25 inches rolling circumference and the "M" is 26.
 
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