Ok I know this is a totally noob question... but it's so noob I couldn't find an answer by searching because it's probably so obvious to most of you.

What exactly is the difference between the 15 inch sized wheel and the optional 16 inch sized wheel? Is there a visual difference in size of tire, clearance, etc? Is there a performance difference in speed, cornering, or fuel economy?

Note that I'm getting a Cooper (non-S) and a primary concern is fuel economy -- but of course I want it to look great too.

Thanks in advance!

 

Well, the overall tire diameter will stay the same, it's just the sidewall height that will adjust for the larger diameter wheel.

Example: 15" wheel/tire is 24" in diameter. Sidewall = 4.5"
16" wheel/tire is 24" in diameter. Sidewall = 4.0"

Make sense? Basically, the shorter the sidewall, the less "roll under" during cornering, but less ability to absorb imperfections in the road.

This is a very general description, but hopefully you get the point.

However, I think the optional 16" tires are "runflats", which means the sidewalls are VERY thick so the tire will not compress due to loss of air. This results in a VERY harsh-riding tire.

I ordered my Clubman and kept the stock 15" wheels and have ordered aftermarket 17" wheels w/ non-runflat tires that will hopefully ride about as good as the stock 15"s.

To me, the lower sidewall just has a much better visual appearance on the MINI's.

 

Welcom msduncan!
I got the 15" wheels mainly because of the potholes and Ice heaves in my area. Yes maybe the 16 or 17" would be cool, but that extra bit of tire height helps on bad roads. My milage is great: 41 to 44 MPG...Now if I had better roads and drove less than 500 miles a week my options would be different.