Will 15" Miata wheels fit my xB? I guess the offset would probably be wrong, but is the bolt pattern a 4x100 like my Miata?

 

They will fit around the lugs... clearing the calipers might be a different story...

 

well check the offset, hub sizes, and bolt pattern, if the miata hub size is bigger or the same to your scion, then it'll work as long as the offset clears the caliper, and the bolt pattern is the same...

 

What is the offset on my factory stock xB wheels in mm?

 

It's either 38 or 42, I can never remember.

 

38

 

I believe the Miata wheels have a 45mm offset. Even if they fit, I wonder what that would do to handling?

 

Everythihng else will fit, but like already stated, your front calipers would probably crash against the spokes. When I had some 15x6.5 +38 Rota Grids on my box, the spokes just barely cleared the calipers. I'm talking about 1 to 2 mm of clearance. They were that close.

 

the question above (38 or 42) refered to stock xB steelers

 

Was it ever determined whether or not the 99-00 Miata 15" alloys fit?

 

Yes, in fact, all 1990-2005 Miata wheels will fit. The center hub opening is 54.1mm, exactly matches the Scion too. There are lots of Miata wheels on the used market, so this is a relatively cheap mod that eliminates those dorky plastic wheelcovers.

We are running 2002 Miata 15" alloys on our 2005 xB. It drives and handles great.