[pardus]

My F34 GT 335 xdrive comes stock with F 225/45/19 R255/40/19 which is a 27" overall Diameter which is 1" larger than the F30's at 26"

Seems like I should be able to put 21" rims on but not finding a lot of options in tire size that would work.

I currently have 12mm spacers on the front with 15mm on the back and rims are 19" M double spoke 598M. no prob in the back for rubbing but grazing in the front on the inside liner when turning.

I would like to match the offset to my current setup without having to use spacers if possible.

How close do front and back overall diameters have to match and any help finding some combinations that work would be much appreciated.


27" Tire Diameter

245/35R21 = 27.8x9.7R21
255/30R21 = 27x10R21
265/30R21 = 27.3x10.4R21
275/30R21 = 27.5x10.8R21
285/30R21 = 27.7x11.2R21
305/25R21 = 27x12R21
325/25R21 = 27.4x12.8R21

[Joe_E]

I'm just curious, why do you want 21's? Seem too large for the car

[pardus]

I don't think they are too large. Proportionally would be the same as 20's on a f30 as the GT has a 1" larger diamtre stock than f30. The GT is a bigger vehicle too, 8" longer and taller.

[.BMW.]

I agree that 21" will work on F34!

If it's important with a staggered setup there will not be many choices though.

245/35-21 front and 285/30-21 rear is the best combo, with almost identical front and rear diameters (the difference should be below 1% with xDrive).

8.5x21" front wheels with offset around 30 and 10x21" rear wheels with offset around 40 is a good start when searching for wheels.

I like to add that I personally never worked with an aggressive fitment for F34 so these numbers are based on the spec for the 19" M Sport wheels that BMW delivers from factory.

Since the tire sizes above are both taller and wider than OEM tires there is always a risk for rubbing.

[pardus]

bump

[pardus]

Well spring is on it's way and will be getting the winters off in the next month and need to sort out my summer setup. I have been looking for 21" wheel and tire combos but there are not a lot of options out there.

Looks like will have to go with this staggered tire size.

245/35R21 = 27.8x9.7R21
285/30R21 = 27.7x11.2R21


When buying online, how do I figure out the right wheel that will be able to fit based on current wheel offset and spacers? Do I need to know backspacing and how different that will be for the larger rim?


Current 598M rims with P-zero RFs
8Jx19 ET30 225/45/19 plus 12mm BMS wheel spacer
9Jx19 ET42 255/40/19 plus 15mm BMS wheel spacer

[F34loner]

Do you have any idea on how to fit 255-40-19R on the front. What size spacers will I need.

[B1GSK1NS]

Hi I know this is an old thread but did you ever get 21 inch wheels on your f34 if so were there any issues?. Thanks

[Billfitz]

21s will ride like a rock.

[J555]

It's the same sidewall height as with 20" on F30, no problem here. The unsprung weight of casted 21" ain't good, so lightweight forged rims are certainly a good idea, if budget allows...