My wife's Subaru has rims that measure 17" from outside edge to outside edge. The car has 16 inch tires.

My Chevy Nova measures 14" and has 13" tires.

My Taco measures 17" and has 16" tires.

If you measure the rims from inside well to inside well, you get something less than the mounted tire size.

1) So what is the proper way to measure a rim? It seems to be "Measure the diameter from edge to edge and subtract one inch." Is this correct?

2) Somebody has told me on this site that I can't mount 15 inch rims on my 07 Tacoma. I must have 16" Rims. Why? Are the six studs on my Taco's hub spaced differently so that a 15 inch rim won't fit?

I am considering purchasing dedicated snow tires and rims for this winter and 16 inch rims seem hard to find than 15s.

Thanks

 

Usually the brakes are the probleem. 15" are not big enough to clear them.

 

How to measure wheels:
- http://www.4crawler.com/Diesel/Tires.shtml#WHEELS

Diameter and width are both measured where the tire bead sits, so hard to get exact measurements externally. Best bet is to look for the mfg. stamp on the wheel, will give both:

 

Okay, thanks!