[matowi]

Folks,

I have had a major headache recently, trying to make up my mind about the correct tire size for my rear wheels in my summer set up.

I will have 20" rims (once BBS finally delivers the CI-Rs I ordered back in February... :/ ) and need to decide two things:

1) Run-Flats or regular rubber. I hoped to go for Michelin Pilot Super Sport tires and these aren't available in Run-Flat version in the BMW-recommended sizes

2) 275/30 or 285/30 for the rear wheels. In every BMW authorized dealership they tell me I CANNOT go for 285/30 as this will immediately void BMW warranty for the x-drive system and other rear suspension parts.

I don't understand that at all. When you measure across, 245/35/20 wheels are identical to 285/30/20 (ca. 680 mm). And 275/30/20 are about 7mm smaller.

Do you have a view on that or any experience with warranty issues? Is there any risk to the rear suspension if I put 285s instead of 275s?

Thanks
m.

[remmib]

I assume BMW are telling you that because the 285/30/20 isn't listed as an OEM tire size option for the F10.
And if you're getting the 20x10.5 BBS CI-R, I'd get 285 because of the width.

[matowi]

Originally Posted by remmib

I assume BMW are telling you that because the 285/30/20 isn't listed as an OEM tire size option for the F10.
And if you're getting the 20x10.5 BBS CI-R, I'd get 285 because of the width.

Thanks remmib,

The thing is whether I CAN put wheels in not OEM-recommended size on my car WITHOUT losing warranty. I have a 2-months old, leased car, so this is a valid question for me...

And because of the BMW's answer I changed the rear rims to 9,5x20". By the way BBS expects CI-R rims to start being delivered only in mid-May :/ ... I'm getting frustrated with this waiting (order placed in February)

[remmib]

Originally Posted by matowi

Thanks remmib,

The thing is whether I CAN put wheels in not OEM-recommended size on my car WITHOUT losing warranty. I have a 2-months old, leased car, so this is a valid question for me...

And because of the BMW's answer I changed the rear rims to 9,5x20". By the way BBS expects CI-R rims to start being delivered only in mid-May :/ ... I'm getting frustrated with this waiting (order placed in February)

Well, if you're going with the 20x8.5 and 20x9.5 sizes wheels, the OEM sized 245 + 275 will be a go fit anyway.

[matowi]

Yes, they will. But 285s on 10,5" look sooooo much better

Thing is, if you're spending so much on that stuff, you want it to put a smile on your face every time you look at the car.

The way things look, I'm pushed into a compromise which will make me smile much less :/

Hence the persistent questions . Is there any danger to the xdrive system if I decide to go with the wider 285s...?

[EmArAsOnS]

Originally Posted by matowi

And because of the BMW's answer I changed the rear rims to 9,5x20". By the way BBS expects CI-R rims to start being delivered only in mid-May :/ ... I'm getting frustrated with this waiting (order placed in February)

BMW is just following standards...
Since u've already changed it to 9,5 then stick with that.
Btw What i heard from BAANVELGEN is that they expect the CI-R to be delivered (to them) late april/beginning of may.

Hopefully we get to see some pics when your new shoes r on
....the wating game is almost over

[remmib]

Originally Posted by EmArAsOnS

BMW is just following standards...
Since u've already changed it to 9,5 then stick with that.
Btw What i heard from BAANVELGEN is that they expect the CI-R to be delivered (to them) late april/beginning of may.

Hopefully we get to see some pics when your new shoes r on
....the wating game is almost over

Are you thinking about getting the new CI-R wheels?

[EmArAsOnS]

Originally Posted by remmib

Are you thinking about getting the new CI-R wheels?

Long story short... Was getting a quote for the 3D design diffuser and asking about RZ-D in case they would get them one day (contacting BBS Japan is a pain ) so they mentioned CI-R and the expected delivery date. Since RZ-D is out l, i am undecided on whether i should go OEM or pull the trigger on the CI-R. Hate waiting tbh and the summer is short as u know

[dan the man]

If you have a x-Drive car 245/35/20 fronts (26.8in) and 285/30/20 rears (26.8in) are the way to go because of the same overall diameter. X-Drive system will not be happy with more than 1% difference in overall diameter between the 2 axes. Going for 245/35/20 fronts (26.8in) and 275/30/20 rears (26.5in) probably will get you in trouble. Looks like BMW authorized dealers in Europe are bunch of morons.
Also you will not find Michelin PSS in 275/30/20 size if want to go with this brand.

Originally Posted by matowi

Folks,

I have had a major headache recently, trying to make up my mind about the correct tire size for my rear wheels in my summer set up.

I will have 20" rims (once BBS finally delivers the CI-Rs I ordered back in February... :/ ) and need to decide two things:

1) Run-Flats or regular rubber. I hoped to go for Michelin Pilot Super Sport tires and these aren't available in Run-Flat version in the BMW-recommended sizes

2) 275/30 or 285/30 for the rear wheels. In every BMW authorized dealership they tell me I CANNOT go for 285/30 as this will immediately void BMW warranty for the x-drive system and other rear suspension parts.

I don't understand that at all. When you measure across, 245/35/20 wheels are identical to 285/30/20 (ca. 680 mm). And 275/30/20 are about 7mm smaller.

Do you have a view on that or any experience with warranty issues? Is there any risk to the rear suspension if I put 285s instead of 275s?

Thanks
m.

[matowi]

Dan,

My thinking was the same: go for 285/30 on the rear axle as their diameter is (almost) identical to the 245/35 up front.

However: no go. BMW's official response was that I have to use 275s or lose the warranty. No rationale provided.

I opted for Pirelli P Zero-s in non-RoF version instead of the Michelin PSS, which are not available, as you rightly said ...

[remmib]

Originally Posted by dan the man

If you have a x-Drive car 245/35/20 fronts (26.8in) and 285/30/20 rears (26.8in) are the way to go because of the same overall diameter. X-Drive system will not be happy with more than 1% difference in overall diameter between the 2 axes. Going for 245/35/20 fronts (26.8in) and 275/30/20 rears (26.5in) probably will get you in trouble. Looks like BMW authorized dealers in Europe are bunch of morons.
Also you will not find Michelin PSS in 275/30/20 size if want to go with this brand.

I haven't seen anybody posting any problems running 245/35 + 285/30, but BMW uses 245/35/20 + 275/30/20 on their 20" OEM for the F10 (and 6-series F12/13 for that matter).