[AswB58]

Okay I'm new to forums in general and most things wheel/tire wise, so please be nice.

Anyway I'm trying to run a 18inch 245 squared all season (Michelin CrossClimate 2s) and want to get an idea of what size wheel I need. Currently have summer 225/40/r18 on the fronts and 255/45/r18 on the rears.

I know the bolt pattern is 5x114 (maybe?), and i also know that messing with sidewall sizes affect the speedometer accuracy. So would it be ok to run a 45 sidewall all around without messing up the speedometer too much? Or do I stick with 40F and 45R?

Also what offset would be best +35? And wide(?) of wheel would I need 8, 9, 9.5? Would I be able to run this tire size on stock wheels?

I mainly use my car as a grand tourer and want to get rid of the runflats and hopefully be able to rotate tires.

If this has already been answered in another thread please point me in the right direction. Thanks

[Expert@ApexWheels]

Originally Posted by AswB58

Okay I'm new to forums in general and most things wheel/tire wise, so please be nice.

Anyway I'm trying to run a 18inch 245 squared all season (Michelin CrossClimate 2s) and want to get an idea of what size wheel I need. Currently have summer 225/40/r18 on the fronts and 255/45/r18 on the rears.

I know the bolt pattern is 5x114 (maybe?), and i also know that messing with sidewall sizes affect the speedometer accuracy. So would it be ok to run a 45 sidewall all around without messing up the speedometer too much? Or do I stick with 40F and 45R?

Also what offset would be best +35? And wide(?) of wheel would I need 8, 9, 9.5? Would I be able to run this tire size on stock wheels?

I mainly use my car as a grand tourer and want to get rid of the runflats and hopefully be able to rotate tires.

If this has already been answered in another thread please point me in the right direction. Thanks

A ton of threads answer some of these questions, but the important stuff for the G20:

Bolt pattern is 5x112, centerbore is 66.6mm (sometimes listed 66.5) Don't get 5x114. The OE wheel bolts are 60° conical seats.

Sidewall height does matter and it depends on the width of the tire you run as well as the wheel fitment. 8, 8.5, 9 are all fine for a 245. I wouldn't do a 245 on a 9.5 unless it was a weird tire like a slick.

Ideal offset depends on the width. Our 18x9" wheel is an ET25 and it works well:


Photocredit to bray : https://g20.bimmerpost.com/forums/sh...&postcount=655

The narrower wheels will likely be fine in an ET25-35 offset range, potentially more. OE wheels
are available in the width range to support what you're trying to do, but you'll need to research those options.

If you're going aftermarket and you have the larger optional brake package on the car, check with the manufacturer that the spokes/barrel of the wheel will clear the brakes. We take a ton of time engineering our wheels to clear brakes with our stuff, but you can have the perfect width, offset, and tire dialed in but end up with immediate brake contact which isn't fun.

Info on our setups is here if it helps, I've built out tire notes. Our stuff leans towards the wider end of the spectrum though so not exactly what you're looking for: https://apexwheels.com/fitment-guide...-fitment-guide

-Tom