[CPAonthemove]

Hey folks,

I drive a 2023 X5 xDrive 45e, and I'm looking into swapping my factory, non-staggered 20" 740M wheels for a set of staggered 21" 741M. However:
1) I want the speedometer to remain accurate (so overall diameter has to be the about the same), and
2) I *definitely* don't want to harm the xDrive system.

My current 740Ms are on the factory Pirelli Scorpion All-Season run-flats. The tire size for both front and rear are 275/45/R20. The 740M wheels are squared and are 9" in width from what I've read online.

From what I can tell, the 741Ms are 9.5" in the front and 10.5" in the back.

Tire math confuses the heck outta me, so I was wondering if I could get some help determining what size tires I should get to fulfill the two requirements above. I'm trying to keep the overall impact to fuel economy and handling to a minimum. If anyone else has done this same exact swap, I'd love to hear what tires you ended up going with.

[eelnoraa]

If you want stagger, just match stock 21” setup. 275/40R21 front , 315/35R21 rear. If you want spare, just use the front size for all 4 corner.

[jad03060]

The user's manual lists all of the tire sizes that will produce the same OD.

It's not all that hard to figure it out and there are online calculators that will do it for you, but take the width, multiply that by the height/100, double that, divide by 25.4 to get inches, and add it to the wheel size. For example 325x35/100=113.75. Now, that's in millimeters, so divide by 25.4 to get inches =4.47. Since it's on both sides of the wheel, 8.94" +21"=29.94" outside diameter. Do that for all of the OEM sizes, and they'll be within a few percent of each other which will keep the odometer, speedometer, and X-drive all happy.

[mojoJJ]

I’m looking into this too. The problem is - if you want OEM size, there’s only one all season tire (Pirelli Scorpion Verde AS). Other than that, you’ll have to get taller tires, which will affect the speedometer and odo by about 3% (they’re similar diameter so xDrive should be fine, there are a lot of people here who are on this setup without any issues).

tl;dr - don’t get 21” staggered wheels if you’d like all season tires on them.

PS - if you still insist, I’ll buy your 20” wheels.

[CPAonthemove]

Originally Posted by mojoJJ

I’m looking into this too. The problem is - if you want OEM size, there’s only one all season tire (Pirelli Scorpion Verde AS). Other than that, you’ll have to get taller tires, which will affect the speedometer and odo by about 3% (they’re similar diameter so xDrive should be fine, there are a lot of people here who are on this setup without any issues).

tl;dr - don’t get 21” staggered wheels if you’d like all season tires on them.

PS - if you still insist, I’ll buy your 20” wheels.

That's a bummer - is that a decent tire? I looked up other tires in the 315/35R21 size and also found the Continental ProContact TX, which has "okay" reviews. Could I get away with going for a skinnier tire than 315 in the rear if it means the diameter won't change much?

[eelnoraa]

Originally Posted by CPAonthemove

That's a bummer - is that a decent tire? I looked up other tires in the 315/35R21 size and also found the Continental ProContact TX, which has "okay" reviews. Could I get away with going for a skinnier tire than 315 in the rear if it means the diameter won't change much?

You can but you also need to adjust the side wall profile accordingly. Use site like this to play with the combinations. I would say shot for within +/-1% difference.

https://tiresize.com/calculator/

[slicky]

Originally Posted by CPAonthemove

That's a bummer - is that a decent tire? I looked up other tires in the 315/35R21 size and also found the Continental ProContact TX, which has "okay" reviews. Could I get away with going for a skinnier tire than 315 in the rear if it means the diameter won't change much?

Its a terrible tire. There really isn't a perfect solution. After wasting way too much time on this subject, I've concluded that it needs to either be 295 all around, 275/45 and 315/40 or a different oem size tire front to back.
Dont shoot for 1% difference front to back. It is meant to accommodate a difference in tread depth, not missmatched tire sizes.

[mojoJJ]

Yeah that’s why I’m thinking of going taller with the Michelin Primacy Tour AS. A few people here have done that without any problems and it’s a better tire than the OEM size Pirelli Scorpion Verde.

Michelin Primacy Tour AS
275/45/21 Front
315/40/21 Rear

[nZtiZia]

funny, i actually did the opposite. i changed from stock staggered 21" to squared 20" because of the lack of all-season run flat availability in OEM 21" sizes and couldn't be happier

[mojoJJ]

Originally Posted by nZtiZia

funny, i actually did the opposite. i changed from stock staggered 21" to squared 20" because of the lack of all-season run flat availability in OEM 21" sizes and couldn't be happier

Yeah I might end up doing the same but I want OEM 20” 740m rims and couldn’t really find a good deal. I’m skeptical going with eBay stuff. So I’ll try out the Michelins for however long they’ll last and then reassess or move on to a different vehicle.