Using a different size tire/wheel as spare

fess · 7th September 2005, 15:10

I need to get a set of winter tires and wheels for my '03. It currently has the stock 18" wheels. I've heard 17" tires are better for snow, but I would like the option of being able use a wheel from 1 set to act as a spare for the other set in an emergency.

If I get 17" wheels, would I be able to put one on with the 18's or visa-versa in an emergency without screwing something up?

gsfent · 7th September 2005, 15:38

Quote:

Originally Posted by fess

I need to get a set of winter tires and wheels for my '03. It currently has the stock 18" wheels. I've heard 17" tires are better for snow, but I would like the option of being able use a wheel from 1 set to act as a spare for the other set in an emergency.

If I get 17" wheels, would I be able to put one on with the 18's or visa-versa in an emergency without screwing something up?

Rolling diameter of stock tire is about 25.7 inches. So as long as the diameter is substantially the same, you can use a different wheel size. a 245/45-17 is the same size, although I don't know if that is a size regularly stocked. For snows a narrower (narrower is better) 225/50-17 at 25.9 inches, if a current stocked size, would be close enough.
Regards,
Jerry

Need4Spd · 7th September 2005, 15:44

Finding a 17" wheel that will clear the brakes will be the hard part. But if you can, what you'd want in a tire is the same diameter as your summer 18s. If they are the same diameter, you should be able to use one of the summers as an emergency spare, but obviously, you shouldn't drive normally with it mounted and get the other one fixed asap. You mainly run into problems if the tires have a different diameter, as that not only messes up the traction control but could wear the differential if mounted on the rear (the different rotation rates will cause wear on the friction plates of the limited slip differential). Hopefully, people who actually live in snow belt climates will chime in here with further advice.

DZeckhausen · 8th September 2005, 00:13

A 17x8" BMW Style 66M wheel can be used as a spare, since it will clear the M5 factory brakes. It will even clear the StopTech 355mm front and 345mm rear brake kits.

If you don't mind the look of an aftermarket wheel, the Borbet Type E will clear the stock brakes, as well as Brembo and StopTech big brake kits. And the cost is far lower.

Either wheel can be used for snow tires in 235/45-17 size.

BMW Style 66M wheel in 17x8" size (front)
Crevier BMW sells these for $391 each. List is $510 each

Borbet Type E in 17x8" size
Tire Rack sells these for $149 each