[ElloM8]

Originally Posted by snowbimmer

This is where I wanted to go when I went wider (255 F & 295 R), but chickened out and stayed at OEM height - a lot of it due to my dealer being adamantly opposed to going up a profile. You, and several others here keep proving that by just keeping the front and back heights the same you won't screw up the x-drive. I had the option of 32 and 25 front offset - I went with the 32 but felt the 25 would have still been ok. I'm at a 45 in the year, so you're out an additional 3mm.

BTW, I think being off by 2 mph would actually put your car at the real MPH - due to BMW speedos understating the speed by about 2 mph. (If I'm doing the math right. Math is hard.)

Looks great.

Yeah, the dealer will always steer you away from anything out of spec. I'm sure this is because clients will ask if they can go 1 size larger on the tire, get the answer & then put it on a rim with a -12 offset and blame them because they said is was ok. Based on Waze & Draggy the speedometer is off. I have oversized tires on my truck so I'm use to dealing with those small discrepancies. BTW, I probably would have went with the 32 offset just to be safe as well. That way if you want a little more, you can add a spacer. Nothing you can do if it's to aggressive/poking out... aside from sell them & try again. ; )

[Moopai]

Thanks for the clarification! One more question, if I leave the front at 245/35R20 but want to go a little wider in the rear, is it then safe to go with 285/30/R20?

Originally Posted by snowbimmer

You gotta go 40/35 (OEM height is 35/30) to keep the diameters in line because the front tires are so effing narrow (245 OEM for the fronts). The OEM 245/35/20 and 275/30/20 will have about 1/4" difference (front bigger). The 255/35/20 and 295/30/20 will narrow that gap to about 1/16"

M5s and M8s run 275/285, so they can run a 35 profile all the way around.

I don't know why they would put such small tires (M850) on such a big effing car. I can see where they want to keep the M8 special, but when you strip out all the special stuff in an M8 you still have an M850 that is just as long, just as heavy and almost as fast. Makes no sense, but that's just me. Physics doesn't take a vacation. Ever.

And the low profile tires make the ride less compliant and the car more susceptible to bent rims - which I did to my relatively new Vossens fairly quickly.

[Dasky_spas]

275/35/20 square works nicely! Had this on for nearly a year with no issues.

[snowbimmer]

Originally Posted by Moopai

Thanks for the clarification! One more question, if I leave the front at 245/35R20 but want to go a little wider in the rear, is it then safe to go with 285/30/R20?

The 245/35 275/30 gives the fronts about 6mm larger in diameter. Going to 285 in back would make difference virtually zero, in other words, front and back will now be the same diameter. Not being a BMW x-drive engineer, I can't say if the transmissions are precisely tweaked to compensate for the original 6mm difference - nor if closing that gap has any adverse effects on the x-drive. I don't see how it could, as recommended snow sets change this dynamic all the time. My M5 snow tires had a front that decreased the diameter by 6mm while increasing the back diameters by 3mm. A net increase of 9mm over OEM. So, you're probably. fine.

This a good website for this stuff:
https://willtheyfit.com/

[Moopai]

Thank you!

Originally Posted by snowbimmer

The 245/35 275/30 gives the fronts about 6mm larger in diameter. Going to 285 in back would make difference virtually zero, in other words, front and back will now be the same diameter. Not being a BMW x-drive engineer, I can't say if the transmissions are precisely tweaked to compensate for the original 6mm difference - nor if closing that gap has any adverse effects on the x-drive. I don't see how it could, as recommended snow sets change this dynamic all the time. My M5 snow tires had a front that decreased the diameter by 6mm while increasing the back diameters by 3mm. A net increase of 9mm over OEM. So, you're probably. fine.

This a good website for this stuff:
https://willtheyfit.com/

[skilz4u2nv]

Originally Posted by ElloM8

Bull S**T! I run 295/35/20 on the rear and 255/40/20 on the front. I also have a +27 offset on the front and a +42 on the rear. I have NO rubbing. That includes when the car is loaded down with crap. It throws the speed off by about 2mph at 70. The ride is fantastic.

Thank you for the confidence boost!

I have the factory 728m staggered wheels which i think have an offset that still works with this tire setup

I go in later today to get them done at my local tire shop. Will keep everyone posted

[skilz4u2nv]

All done and surprise surprise they fit!

255/40/20 Front
285/35/20 Rear
On the stock 728m wheels

Thank you all for your help! You guys are the real MVP!

[Moopai]

Can you post some pictures? Close up please.

Originally Posted by skilz4u2nv

All done and surprise surprise they fit!

255/40/20 Front
285/35/20 Rear
On the stock 728m wheels

Thank you all for your help! You guys are the real MVP!

[ElloM8]

Originally Posted by skilz4u2nv

All done and surprise surprise they fit!

255/40/20 Front
285/35/20 Rear
On the stock 728m wheels

Thank you all for your help! You guys are the real MVP!

Yep! all you did is swing your variable the opposite direction of mine.
I'm 28.1 (circumference) on the rear and 28 on the front. You are 28 on the front & 27.9 on the rear. Congrats! Now you don't have to regret listening to the dealer every time you look back at it. ; ) Plus the ride will be much better.

[skilz4u2nv]

Don't mind the dirty salty car... its been snowy and cold up here