Spare tire question

[X5 Meister]

I was wondering if anyone might know which scenario is better for dealing with a flat tire?

A. Running on a full size spare that is smaller in diameter than the other 3 tires? (i.e. X5 has 19" tires and spare is a 17" or 18" full size spare)

B. Running on a temporary spare tire that is the same diameter as the other tires.

I don't have the answer, but hopefully some pro out there knows.

[PersonaNonGrata]

Originally Posted by mgruber

I was wondering if anyone might know which scenario is better for dealing with a flat tire?

A. Running on a full size spare that is smaller in diameter than the other 3 tires? (i.e. X5 has 19" tires and spare is a 17" or 18" full size spare)

B. Running on a temporary spare tire that is the same diameter as the other tires.

I don't have the answer, but hopefully some pro out there knows.

All E53's, 4.6is and 4.8is excluded, came with a full sized spare mounted on a 17" wheel. The overall diameter should be the same or very close to that of 18", 19", or 20" wheels. If there is a difference, it is nothing to worry about. You can run safely on on the full sized 17" spare. The height of the taller tire and smaller wheel on the 17" versus the shorter sidewall and larger wheel on the 19" wheels pretty much balance out.

There have been more technical discussions about this so a search might give you more info than I can dig out of my aging memory.

[X5 Meister]

Thanks for the information it's very interesting. My question was prompted when I discovered that the 4.6is and 4.8is editions came with temporary spares and not full size spares. Further, those temporary spares are 19" spares. Given that a temporary spare takes up less space in the trunk than a full size 17" tire, I thought maybe I would swap my full size 17 for a temp 19" which coincidently would go well (I think) with my 19" sport wheels.

I'd be very interested in finding out BMW's reasoning for putting a 19" temp spare in the 'is models which as everyone knows have 20" wheels. Maybe they felt that the 17" full size was too big a difference from the 20"? And maybe an 18" or 19" full size spare was either too big for the trunk or too expensive?

[Eurosport]

well the reason why they didn't put the full 17's in the 4.6 and 4.8 is because it won't clear the brake calipers on those cars, that's why you'll never see a 4.6, 4.8 with 17's on as winter setup they have to go 18's

[X5 Meister]

I didn't know that bit about the 17's and the brake calipers. Though I assume you are referring to the fronts only since all three (4.4/4.6/4.8) have the same rear brake setup.