Newbie Considering 2011 X5

[jcmd2003]

Originally Posted by barbja

jcmd2003, look at the size written on the side of the tires. The front should be 255/50 R19. The back would be either the same as the front for 19" or 285/45 R19 for 10"

I already know my tire size; they are 255s all around. If you want to know your rim width you should probably use a tape measure rather than assuming your rim width based on the tire aspect.

[barbja]

Originally Posted by jcmd2003

I already know my tire size; they are 255s all around. If you want to know your rim width you should probably use a tape measure rather than assuming your rim width based on the tire aspect.

Eh? Staggered wheels do not use the same tire size all the way around. A wider wheel must use a tire with a larger section width in order to match the bead and hold air in the tire.

The 335 9" uses 255/50-19, 10" uses 285/45-19.

Just like for 214 20" staggered: 9": 275/40-20 10": 315/35-20

If you have 255 all around (written on the tire), that is 255mm, or ~10". Now, that's the section width of the TIRE, not the width of the rim. X5 10" rims take 315s=315mm=12.4". (Little wider rim, little fatter tire...)

If you put a 255 (10") tire on a 10" rim, it wouldn't hold air.

Perhaps I may not know exactly the width of the rim from the section width of the tire, but I DO know that if I have the same section width on all the tires on my car, all the rims on the car are the same width.

And, given those previous two statements, given that we know that a 255 tire can't run on a 10" wide rim, and all I have left is to be running 9" all around (because the only choice I have for 335 is 9" or 10").

Is there a flaw in that logic?

However, I did as you suggested and went out and did my best to measure the width of the rims mounted on my car. Both front and rear appeared to be 10". HOWEVER, that is the "overall rim width". The number that we are concerned with here is the "rim width", which is measured from the inside shoulder to the inside shoulder of the rim lip, which can only be done if you remove the tire. If the overall rim width is 10", then there is no way that the rim width can be 10". Which again, doesn't guarantee that my rims are 9", but by process of elimination with these specific wheels, leaves us with 9".

So -- 9" all around for the 35i Sport Activity also? (since there's 255/50-19s all around)

[jcmd2003]

Originally Posted by barbja

Eh? Staggered wheels do not use the same tire size all the way around. A wider wheel must use a tire with a larger section width in order to match the bead and hold air in the tire.

The 335 9" uses 255/50-19, 10" uses 285/45-19.

Just like for 214 20" staggered: 9": 275/40-20 10": 315/35-20

If you have 255 all around (written on the tire), that is 255mm, or ~10". Now, that's the section width of the TIRE, not the width of the rim. X5 10" rims take 315s=315mm=12.4". (Little wider rim, little fatter tire...)

If you put a 255 (10") tire on a 10" rim, it wouldn't hold air.

Perhaps I may not know exactly the width of the rim from the section width of the tire, but I DO know that if I have the same section width on all the tires on my car, all the rims on the car are the same width.

And, given those previous two statements, given that we know that a 255 tire can't run on a 10" wide rim, and all I have left is to be running 9" all around (because the only choice I have for 335 is 9" or 10").

Is there a flaw in that logic?

However, I did as you suggested and went out and did my best to measure the width of the rims mounted on my car. Both front and rear appeared to be 10". HOWEVER, that is the "overall rim width". The number that we are concerned with here is the "rim width", which is measured from the inside shoulder to the inside shoulder of the rim lip, which can only be done if you remove the tire. If the overall rim width is 10", then there is no way that the rim width can be 10". Which again, doesn't guarantee that my rims are 9", but by process of elimination with these specific wheels, leaves us with 9".

So -- 9" all around for the 35i Sport Activity also? (since there's 255/50-19s all around)

Hmmm. I don't dispute your logic, but there are a range of rim widths that tires of a particular size can accomodate. The 255s are only designed for rims up to 9" according to Tirerack, so that makes it more likely that the rims are 9". I attempted to measure from rim edge to rim edge where the tire was seated and came up with the 10 1/4", but if you say the only way to accurately gauge it is with the tire off, I'll take your word for it and assume they are 9s.

There have been enough discrepancies, at least in my ordering process, between the website configurator, BMW.com, BMWUSA.com, and the SA's information that I personally would not rely on what tire width they put on the rims to guarantee that the rims are 9s and not 10s.

The only reason I have any concern about it is that I have considered adding spacers/fender flares, and knowing the width of the rim is crucial for those calculations.

[barbja]

Yes, I know. I'm finding it extremely odd that all the information we currently have from BMW (from a BMW parts guy and a BMW brochure) is showing that the 335s are staggered 9"/10".

But our real-world measurements of what is actually on the car, and the data on the sides of the tires, all seem be pointing to a set of uniform 9".

Also, if I just look at the back of my car, it doesn't look nearly as "burly" as the cars with the 20" rims. The fact that the rims are 20" in diameter shouldn't be evident from the rear, only the width. So my 19"ers must be more svelte. jcmd2003, do you have the same impression?

Should we be going into our dealers asking for our 10" rears?? Unite!