[540xi Lci]

Hello guys,

here it goes…
Want to change my 19’ wheels 245/40/19 & 275/35/19 to 20’ or even maybe 21’ wheels.
For 20’ it should be 275/30/20 at the back but i dont want lower sidewall, i love 275/35 like it goes on 7 series…
Can i just go for 275/35/20 at the back?
Really dont know how to calculate diameter etc…
I just know if its Xdrive that i cant mess with sizes.
As for 21’ , it doesent come OEM in 8 series as far as i know.. is it possible to put 21’ on my car and what tyre dimensions should i go?
Thanks!

[Wavy]

You have to keep the height difference between front and rear tires close to the same since it's X-Drive. I have 22s so 21s will fit fine as long as you get the correct offset. If you want a beefier looking fitment you could do a 265/30/21 front and 295/25/21 or 305/25/21 rear.

[Wavy]

This is mine with 305s in the rear

[540xi Lci]

Originally Posted by Wavy

This is mine with 305s in the rear

Wow.. looks awesome
Like a boat

And what about people calculating wheel spin etc..?
Not really expert for that
I was looking at m8 OEM 20’ but seller told me i cant put it on regular 8series since they are too wide

[Wavy]

You can use this website to compare different tire sizes and it'll tell you how much the speedo will be off

https://tiresize.com/calculator/

M8 wheels will poke out on a regular 8 because the offset of the M8 is lower.

[540xi Lci]

Originally Posted by Wavy

You can use this website to compare different tire sizes and it'll tell you how much the speedo will be off

https://tiresize.com/calculator/

M8 wheels will poke out on a regular 8 because the offset of the M8 is lower.

Compared to my current setup , the 305/25/21 seems very similiar, diameter +1.5% and revs/mile -12
Guess thats no problem for Xdrive.
Thanks for the help! If you ever need something from Europe maybe i can Help

[Dasky_spas]

Non sense- I run 275/35/20 square on my m850. You can't run m8 rear wheels bc they M8 rear axle is shorter.

[Dasky_spas]

Running 4 M8 front wheels here, before and after adding the m8 front body panels and 12mm spacers. I did have to use 3mm front spacers with the m850 front fenders.

[Moopai]

Your car looks amazing. Doesn't the large tires throw-off your speedo?

Originally Posted by Wavy

This is mine with 305s in the rear

[Wavy]

Originally Posted by Moopai

Your car looks amazing. Doesn't the large tires throw-off your speedo?

Thank you. It's very little because the B8 already comes with taller tires than the M8/8 series so the speedo is calibrated differently.