[walsh]

Is this possible? I think theres no way to get the rolling diameter below 1% off unless you got really skinny wheels. It would suck if this is true. Thanks.

[JeffL]

yes. 235/30/19's and 265/30/19's. The main goal is to keep within the 1% diamater difference between front and rear wheels/tires. for non-staggered you could run 245/35/19's all around depending on wheel offset. That would be way more than a 1% difference than stock but all 4 are the same so you wouldn't have any issues.

[walsh]

Originally Posted by JeffL

yes. 235/30/19's and 265/30/19's. The main goal is to keep within the 1% diamater difference between front and rear wheels/tires. for non-staggered you could run 245/35/19's all around depending on wheel offset. That would be way more than a 1% difference than stock but all 4 are the same so you wouldn't have any issues.

Thanks, my speedometer would be off by a lot though right? because there would def be a big diff from stock?

[louie_perm]

A larger diameter wheel doesn't mean a larger diameter tire. A 245/30-19 is not as tall as a 235/40-18, for example, yet both of them can fit the e90. As the wheel's diameter gets larger, the tire's sidewall must get shorter. That's why the aspect ratio falls from 225/45 at 17" to 225/40 at 18" to 225/35 at 19". The tread widths are the same, the overall diameter of the tire is approximately the same, but the hole in the middle of the tire where the wheel goes is getting bigger as the tire sidewalls are getting shorter.

The point is not to keep the rolling diameter as close as possible to stock. Instead, the point is to keep the rolling diameter as close as possible across the 4 tires. The easiest way to do this is to go non-staggered (same tire on all 4 corners)--whether you use 225/35-19, 235/35-19, 245/30-19, or 255/30-19 doesn't matter, as long as the wheels have the right widths and offsets to keep the tires from rubbing.

If you want to go staggered with the Xi, then 225 (front) and 255 (back) are usually pretty close in rolling diameter, as well as 235/265.

[Nikolas]

Originally Posted by JeffL

yes. 235/30/19's and 265/30/19's. The main goal is to keep within the 1% diamater difference between front and rear wheels/tires. for non-staggered you could run 245/35/19's all around depending on wheel offset. That would be way more than a 1% difference than stock but all 4 are the same so you wouldn't have any issues.

You mean 235/35/19's for the front. 235/30/19 and 265/30/19 is a bad match.

I have 235/35/19 and 275/30/19 which is nearly identical in diameter.

[JaysBlueE92]

what's the best tire sizes to run on xi coupe with 20 inch wheels?

[walsh]

225/35/19 front and 255/30/19 rear is the correct sizing although other setups can work... i was comparing to the wrong stock size... that's where my confusion came from.

[walsh]

Originally Posted by JaysBlueE92

what's the best tire sizes to run on xi coupe with 20 inch wheels?

Good luck with that... I dont think you can even even do staggered 20's on an xi. You'd prob have to run 225/30/20 all the way around and i'm not even sure that would work.

[JaysBlueE92]

Originally Posted by bwalshy99

Good luck with that... I dont think you can even even do staggered 20's on an xi. You'd prob have to run 225/30/20 all the way around and i'm not even sure that would work.

good to know..thanks for the input. I guess it's gonna be 19's then

[JeffL]

Originally Posted by Nikolas

You mean 235/35/19's for the front. 235/30/19 and 265/30/19 is a bad match.

I have 235/35/19 and 275/30/19 which is nearly identical in diameter.

yes 235/35/19. broke my right wrist and typing with a cast is challenging.