[e92space335igray]

Just picked up 4 beautiful 18" 8.5" wide wheels which I plan on running as my winter set up. Trying to figure out what tire sizes to put on it though.
My 2018 430i comes stock with 225s on 8" up front and 255s on the 9" rears.

I was considering trying to do the same exact tire sizes on my four 8.5" wheels because it feels so grippy, handles perfect and looks outstanding.

The alternative would be something like 225s, 235s or 245s on all 4 and making it square just like the wheels.

I understand skinnier tires work better in the snow, but I'm willing to sacrifice some snow performance for better dry performance.

Any thoughts, concerns, advice?

[.BMW.]

Go with a square tire setup with square wheels!

More balanced handling and possibility to rotate tires are good reasons for square.

If you like wider tires go with 235 or 245 all around, three options below:
235/45-18, 669mm (1.5% taller than OEM size)
245/45-18, 677mm (2.7% taller than OEM size)
245/40-18, 653mm (1% shorter than OEM size)

All these tire sizes will fit fine without rubbing.

[e92space335igray]

Originally Posted by .BMW.

Go with a square tire setup with square wheels!

More balanced handling and possibility to rotate tires are good reasons for square.

If you like wider tires go with 235 or 245 all around, three options below:
235/45-18, 669mm (1.5% taller than OEM size)
245/45-18, 677mm (2.7% taller than OEM size)
245/40-18, 653mm (1% shorter than OEM size)

All these tire sizes will fit fine without rubbing.

Thanks for the advice. I’m leaning towards the 245 option and out of the two above the 40 option simply because the -1.2% is a smaller total difference than the +2.7% of the 45. Other than the comfort side effects of more or less sidewall, is there a reason you would rather make it bigger than smaller? Will smaller put more mileage on my odometer or anything like that? Thanks so much for your help.

[kern417]

I went with shorter tires on my aftermarket wheels and haven't had any issues. I think it looks better especially on 18s. The lower profile tire makes the wheels look bigger. And the wider contact patch up front was a welcome improvement.

Also just FYI, your 430i comes with 8.5" wide rears not 9".

[wdeerfield]

i run 235/45/18 winter tires on 18x8.5 wheels



Shorter tires accumulate more miles on the odometer, have less sidewall for protection and make the wheel well gap larger. Going to the 235/45/18 is 26.3 compared to 26 and corrects the speedo in the car as well while not causing any potential rubbing issues that you may encounter with a 245/45/18

[othniel]

Long time lurker, first time poster here now that I've joined the club!

I have the same wheel set up for my 2018 F30 and appreciate the helpful responses - but I have Xdrive. Will I cause issues for the Xdrive system going from the staggered set up to a square winter set up?