[mojoJJ]

tl;dr : happy with Michelin primacy tour AS 275/45/21 315/40/21 tires. No rubbing, no CEL or other problems. Great ride compared to stock performance RF tires.

Heya Fellas!

So after about 2000 miles, I got tired of horrible stock runflats on my LCI X6 40i (no air suspension) and decided to look for something with better ride and all season-ness. Searched the forums and found this thread discussing non-standard sizes and a few forum members running those without any problems and decided to give that a shot.

I ordered Michelin Primacy Tour AS - 275/45/21 and 315/40/21 at America’s Tire. I had talked to dealer service shop foreman and he said (unofficially, off the record) there should be no issues with rubbing or the xDrive system since the front and rear diameters are within 1%.

No rubbing at full lock, no CEL lights or any other problems after driving 300 miles.

The ride quality is so much better, all I hear now is the faint drone of the I6 engine and wind noise. There is of course some noise from rough roads but it’s still all very dampned.

The car obviously doesn’t automatically recognize the size now but I have set it to “winter/all-year” and “other authorized” tire settings in iDrive. As for tire pressure, the system no longer shows recommended tire pressure, it just shows the current tire pressure.

The only question I have is how do I calculate tire pressure for the new set? I used the tire size calculator and it give me suggestions but not sure if that’s accurate? Can someone please confirm? (Attached images)

[915M]

Looks good! I will do it soon too

[Keithwand]

These will be my replacements. Have 11k on pirelli RF on my x5.

[kgelfen360]

Thanks for posting this. I think I am going to have to do the same. Only other option is Pirelle Verde AS in original spec tire.

mojoJJ
Was your original spec 275/40/21 and 315/35/21. I have different 21 inch rims 741M wheels

[roamio]

So increasing diameter of wheels have no effect at all? Then why not go with 275/50/21 and 315/45/21? Just curious.......

[mojoJJ]

Originally Posted by roamio

So increasing diameter of wheels have no effect at all? Then why not go with 275/50/21 and 315/45/21? Just curious.......

I’m pretty sure increase in tire size has consequences somewhere down the road. We’re just trying to find the closest size up with better tire size availability.

We do see cars on the road with crazy tall tires but at some point it’s going to start rubbing on suspension components and within the wheel well. Specially front tires at full steering lock. Even right now, i have less than two fingers space between my front tires and the wheen well sides, so going one size taller might actually not fit.

Other than fitting issues, as you move up from OEM sizes, the overall diameter difference between the front and rear tires becomes significant. The OEM fronts and rears are exactly same diameter, so no issues with drivetrain xDrive systems. My taller tires have a 0.7% diameter difference and that too is acceptable (less than 1% recommended). But now if you go to tires you mentioned, front and rear diameter difference is 1.3% and that would probably cause troubles with xDrive.

[mojoJJ]

Originally Posted by kgelfen360

mojoJJ
Was your original spec 275/40/21 and 315/35/21. I have different 21 inch rims 741M wheels

Yes, that was the OEM spec.

[TexasBimmer89]

Glad to see more people going the route.

Makes me more confident to do it myself for my third set of tires.

Stock Continentals lasted 16k miles. Replacement Pirellis are at 14k and should last another 2k-4K.

Mine is an Sdrive so the rears have worn way faster than the fronts.

[915M]

Originally Posted by roamio

So increasing diameter of wheels have no effect at all? Then why not go with 275/50/21 and 315/45/21? Just curious.......

On top of what mojoJJ explained 275/50/21 and 315/45/21(And also 275/40/21 and 315/35/21) has much less tire choice than 275/45/21 and 315/40/21

[yeh7360]

I am using the same tire set for my 20 X5.
MICHELIN PRIMACY TOUR A/S is perfect.
Front and rear only differ 0.4% based on Tirerack data.

[RBarela]

Any issues lately? How many miles on the new taller sets?
Thanks

[mojoJJ]

Originally Posted by RBarela

Any issues lately? How many miles on the new taller sets?
Thanks

About 5000 miles, no issues.

[Jch99]

How does this affect the warranty if the crank case happens to have issues? I just ordered the Pirelli verde - only option available for the oem spec sizes.

[mojoJJ]

Originally Posted by Jch99

How does this affect the warranty if the crank case happens to have issues? I just ordered the Pirelli verde - only option available for the oem spec sizes.

Yeah that’s probably a problem for warranty claims associated with drivetrain malfunction. That’s a risk I’m able to live with though. But I’ll definitely fight for it.

There’s a thread here talking about how the dealership refused warranty (for a crankcase? IIRC) based on the fact that the member had replaced factory wheels and tires with larger STILL OEM wheels and tires. And there are many other cases where BMW or the dealer has refused warranty based on BS reasons.

[915M]

I was going to write "Why don't you get 19" wheel with snow tires for winter and also for the warranty claim?"

But you guys are from NorCal and Seattle... Not much reason to get snow tires....

[mojoJJ]

Originally Posted by 915M

I was going to write "Why don't you get 19" wheel with snow tires for winter and also for the warranty claim?"

But you guys are from NorCal and Seattle... Not much reason to get snow tires....

Well that and I live in an apartment building so not a lot of space to store a second set of wheels. I have considered replacing with a 20” 740m set but I don’t want to spend a lot of money on a new set and don’t want to have used wheels on my new car just yet. Maybe in the future I’ll replace, and hopefully there are no issues with the drivetrain until then.

[1coolF15D2017]

I just got min installed yesterday and so far so good. But need to find out what is the proper psi for front and back. Today i have it 36 up front and 41 at the back.

[mojoJJ]

Originally Posted by 1coolF15D2017

I just got min installed yesterday and so far so good. But need to find out what is the proper psi for front and back. Today i have it 36 up front and 41 at the back.

I keep 33/36. The tire size website suggests 31/33 but I fear it might be too low.

[eelnoraa]

Originally Posted by roamio

So increasing diameter of wheels have no effect at all? Then why not go with 275/50/21 and 315/45/21? Just curious.......

Clearance. There is a limit on how much you can increase based on that along. Not saying 50 won’t work, but really need experiment.

[1coolF15D2017]

Originally Posted by mojoJJ

I keep 33/36. The tire size website suggests 31/33 but I fear it might be too low.

hmmm. Tried your settings and I am getting low pressure on left rear, although the psi is 36. Same pressure on Right rear and no complains. Reset the TMPS and iDrive still getting the same result. I may have to bump it back up to 41 again to see if the warning goes away.

[mojoJJ]

Originally Posted by 1coolF15D2017

hmmm. Tried your settings and I am getting low pressure on left rear, although the psi is 36. Same pressure on Right rear and no complains. Reset the TMPS and iDrive still getting the same result. I may have to bump it back up to 41 again to see if the warning goes away.

The TPMS won’t work because you’re using a non standard tire. You need to change the tire type/size to “other” in the settings.

[1coolF15D2017]

Originally Posted by mojoJJ

The TPMS won’t work because you’re using a non standard tire. You need to change the tire type/size to “other” in the settings.

Changed it to other, all/Winter. Summer is not selected anymore. That is the first thing i did before i drove off the tire shop. Performed reset twice and iDrive once. I will put it back to 36/41 later today and see what happens.