[Fly320s]

I bought a 2017 M240i X-drive last year. It came on winter tires with the summer tires/wheels included in the sale.

Last week, I put on the summer tires and noticed that one tire is the wrong size. The factory sizes are 225/40ZR18 for the fronts and 245/35ZR18 for the rears. I have three of the 225s and one 245. So, either I am missing the proper 245 rear tire or the previous owner had a square setup and I am missing a 225.

What to do? Is the proper tire size that important? I don't mind buying the correct rear tire size if needed. I don't plan to track the car, so max performance isn't an issue.

Thanks.

[Toddbmw]

What size are the rims? Look on the back of the wheel on one of the spokes.

For a square setup using 225/40ZR18 the factory rim size is 7 1/2 X 18
For a staggered setup using 225/40ZR18 and 245/35ZR18 the factory rim size
is 7 1/2 X 18 for the front and 8 1/2 X 18 for the rear.

Is the 245/35ZR18 tire on a 8 1/2 X 18 rim? if it is, do you have a second 8 1/2 X 18 rim? If so, get a 245/35ZR18 tire for that rim.

If you have 4 - 7 1/2 X 18 rims, then get a 225/40ZR18 to replace the 245/35ZR18 tire.

If you have 3 - 7 1/2 X 18 rims and 1 - 8 1/2 X 18, then you need to source either rim size and mount the matching tire as detailed above.

[aerobod]

Originally Posted by Toddbmw

What size are the rims? Look on the back of the wheel on one of the spokes.

For a square setup using 225/40ZR18 the factory rim size is 7 1/2 X 18
For a staggered setup using 225/40ZR18 and 245/35ZR18 the factory rim size
is 7 1/2 X 18 for the front and 8 1/2 X 18 for the rear.

Is the 245/35ZR18 tire on a 8 1/2 X 18 rim? if it is, do you have a second 8 1/2 X 18 rim? If so, get a 245/35ZR18 tire for that rim.

If you have 4 - 7 1/2 X 18 rims, then get a 225/40ZR18 to replace the 245/35ZR18 tire.

If you have 3 - 7 1/2 X 18 rims and 1 - 8 1/2 X 18, then you need to source either rim size and mount the matching tire as detailed above.

Rear OEM wheel size is actually 8 x 18 on the M240i for staggered fitment of 245/35-18 tyres.

[Toddbmw]

I stand corrected.