[iceman3]

I own a 2016 x3 with m sport package that has staggered 20" wheels. My rears are getting pretty bald so I was going to replace the tires or use the after markets from my 2011 x3 255/40/20 all around. After researching sizes I found that my oem set are different diameters. The rear pirelli's 275/35/20 are 2/10 shorter than the fronts 245/40/20. I was always under the impression that they had to be the same. Does anyone know if the M sport package has a different gear setup to accommodate this or is there a tolerable difference in all of them, and if so how much difference can I have? I called two dealers and of course you aren't allowed to talk to anyone that knows anything, but got two different answers as to whether I can use my same size tires from my 2011.

[________]

Originally Posted by iceman3

I own a 2016 x3 with m sport package that has staggered 20" wheels. My rears are getting pretty bald so I was going to replace the tires or use the after markets from my 2011 x3 255/40/20 all around. After researching sizes I found that my oem set are different diameters. The rear pirelli's 275/35/20 are 2/10 shorter than the fronts 245/40/20. I was always under the impression that they had to be the same. Does anyone know if the M sport package has a different gear setup to accommodate this or is there a tolerable difference in all of them, and if so how much difference can I have? I called two dealers and of course you aren't allowed to talk to anyone that knows anything, but got two different answers as to whether I can use my same size tires from my 2011.

You can use any size you want, as long as the diameter differences are within 1% between axles.

That makes a square setup obviously acceptable, and the OEM staggered sizes too.

Going over 1% is said to overload the transfer case.

[Merlin82]

Ya I think its more about the percentage difference in the revolutions per mile of the tires. When I bought new tires, one of the reasons I bought the continentals is because they were the closest front and back for revs per mile. Plus they were also a little lighter than some of the other options. For some reason I thought that it was up to 3% difference but it may be 1% like Onerdriver said.

[________]

Originally Posted by Merlin82

Ya I think its more about the percentage difference in the revolutions per mile of the tires. When I bought new tires, one of the reasons I bought the continentals is because they were the closest front and back for revs per mile. Plus they were also a little lighter than some of the other options. For some reason I thought that it was up to 3% difference but it may be 1% like Onerdriver said.

3% is the industry recommended maximum diameter difference, so as to not affect the car original dynamics, mostly braking capacity. And it also alters the speedometer reading.

1% is said to be the threshold for XDrive due to the transfer case (it works harder when tires are of different diameter).

[iceman3]

Thanks guys for the help. Can get my wheels on.

[x3sm]

Does anyone know if it makes sense to put a square set up on a X3? Like 275/40 all around with 19x9.5 wheels?

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Originally Posted by x3sm

Does anyone know if it makes sense to put a square set up on a X3? Like 275/40 all around with 19x9.5 wheels?

Why wouldn't a square setup makes sense?
It's how it comes from factory.

In regards to the size you mentioned, the only possible issue would be rubbing up front.

[x3sm]

Originally Posted by OnerDriver

Why wouldn't a square setup makes sense?
It's how it comes from factory.

In regards to the size you mentioned, the only possible issue would be rubbing up front.

You are right... Do you know what the widest tire that can fit in the front? I guess it depends on the wheel width and offset, but any known members with wider than 255 up front?

[Merlin82]

I tried a set of X5 wheels on mine which has the 275's in the front and they just barely rubbed the struts. They would likely fit with a small spacer or maybe different offset. Other than rubbing the strut they didnt seem to contact anywhere else.