[DannyX3]

Hey people,
After some advise. I recently purchased a 2012 X3 2.0 X-drive which has some questionable alloys as standard. The current tyre size is 225/60/17. I am thinking of buying some 18” rims but would like to know what tyre size I require to keen the same rolling distance???
Has anyone put larger alloys on and what was the ride quality difference?
Thanks

[BIG_KID]

245/50-18 would be the factory size tire

[DannyX3]

Thanks for the reply.

Do you know if my calculations are correct?
From the research I have done, correct me if I am wrong.

My tyres - 225/60/17
225mm wide
135mm tyre wall height (60% of width)
270mm (top and bottom)
432 alloy height
Total = 702mm

245/50/18
245mm wide
122.5mm tyre wall height
245mm (top and bottom)
457mm alloy height
Total = 702mm

This would equal overall circumference. Therefore would be okay for Speedo issue and rolling feel.

[BIG_KID]

My math

225 x .040 x .6 x 2 + 17 = 27.8”

245 x .040 x .5 x 2 + 18 = 27.8”

Exactly the same

[DannyX3]

Awesome, thank you.
Out of interest what does the 040 represent?

[BIG_KID]

MM to INCH conversion

[Bilbofraggins]

https://www.wheel-size.com/size/bmw/...xdrive20i--181

[TEF]

Yes, ride quality with the 18" wheel and tires will be negatively affected. My 28d xdrive arrived with 245/50-18 tires and my winter tire set is 225/60-17. The latter rides better and yields better gas mileage. Other than appearance, I don't see any advantage in going with the 18-inch wheels and tires.

[BIG_KID]

Originally Posted by TEF

Other than appearance, I don't see any advantage in going with the 18-inch wheels and tires.

And that’s exactly why I went to the 18” wheels. The 17” are hideous and directional…

[DannyX3]

Originally Posted by BIG_KID

And that’s exactly why I went to the 18” wheels. The 17” are hideous and directional…

It’s the only reason I want to change to 18”.