Tirerack has a nice setup where if you have the JCW you can choose winter wheels to see what 16" wheels will fit. No other company has this. boo to them. The problem is that Tirerack does not sale the wheel I'm looking at.

Tirerack says several 16" wheels will fit. What is the criteria to determine whether a 16" wheel will fit over the JCW brakes? Is there an inside measurement I can give the wheel dealer to see if there will be enough room to clear the calipers? I'm not sure what to do. Obviously the wheel is the correct bolt pattern and the offset is 40 which I would like.

Here is the wheel I'm looking at.

 

For the most part it's the offset that'll determine if they'll fit over the brakes. That Koenig page didn't list the offset though.
Anyway, unless you're going to a much smaller diameter (like 15's or smaller) then the 16's should fit, provided the offset is enough to ensure the spokes sit far enough away from the hub to clear the caliper

Did that make any sense??

 

What he said. All about the offset.

 

Oh, just the offset matters? I was thinking it had to do with the inside measurement of the barrel also. I think the main portion of the rim where the tire is mounted is referred to as the barrel. Some are flat while others are curved inward towards the center of the rim. Thus giving some of the same size rims more of less of an opening inside the rim for proper rotor/caliper ventilation.

 

Well yeah, but I meant, provided the rim is big enough (diameter wise) to fit around the brake caliper/rotor. In that case, then it comes down to offset. The lower the offset the further out the face of the wheel will stick and so the more room you'll have in front of the brakes.