[GenX3]

Is it possible to put a wider tire, say 275 40R19, on the rear of an X3? I see that staggered combination in the users manual and was thinking... hmmm, must be an option when we need new tires.

[xDrive35i]

That is how the 19" 309 summer performance tires come. F245/45/19 and R275/40/19.

[GenX3]

Well, sounds like not only is it possible, it's recommended for summer sport driving. I got the M-Sport, so same size all around. Sounds like you got the Sport package?

I'll be watching the tire wear over the next year or so, but when I replace, I'm going to put on the wider tire on the back.

Thanks,

[richardew]

I don't see that as an option anymore for 2012. You can add the 20" 310's for $5500! Ouch!

[GenX3]

Yeah, I love the 20" wheels, but just can't throw down that kind of cash. I always liked the staggered wheel concept for the sport packages across various cars...

So, when the factory tires run down on my 19 wheels, I'm going to replace the back one's with slightly wider tires (275 rather than 245 roughly an inch wider - the profile is pretty much the same).

[Lotus7]

Originally Posted by GenX3

...So, when the factory tires run down on my 19 wheels, I'm going to replace the back one's with slightly wider tires (275 rather than 245 roughly an inch wider - the profile is pretty much the same).

Just be sure to fit tires with the correct aspect ratio. i.e.: If you use 245/45's in the front than you MUST use 275/40's in the rear. The X3 MUST must use tires having the exact same outside diameter on all four wheels.

245/45 = 27.7 inches O.D
275/40 = 27.7 inches O.D.
That's an acceptable set up

245/45 = 27.7 inches O.D.
275/45 = 28.7 inches O.D.
That's a set up that will destroy the center differential and front/rear proportioning clutch, as well as activate the ABS and stability control systems.

[GenX3]

That's a critical point. I saw the sizes in the manual and did the math to find the aspect ratio was the same and figured it was meant to be that way. But I was unaware of the dangers of getting the wheel's aspect ratio out of balance.

I think there are some folks out there that would love to fill in the wheel well with a larger/bigger tire and this information is an important piece data.

thanks,