While doing a recent brake job I decided to weigh the various wheel and tire combos that are on my car or in my garage. Here they are:

17" (S-lites) with run-flats 45 lbs.
16" (R-84) with run-flats 41 lbs.
16" (R-84) with conventional 38 lbs.
15" (holies) with conventional 29 lbs.

 

See http://www.mini2.com/forum/faq.php?f...heel_tire_tech

You'll have to do the arithmetic yourself.

 

45 lbs. Damn. No wonder my MCS launches so much more quickly when the 15" Blizzaks are mounted.

 

Yes, the S-Lites are HEAVY. I used to have a Cooper of my own, but now only my wife has one. I had smaller, WAY lighter wheels on mine. So much so that just picking one up as opposed to picking up one of my wifes S-Lites you could tell that there was a HUGE weight difference.

With any car, lighter wheels are better in every way as long as they are strong enough, but with these little cars, you can actually feel the difference in acceleration by bolting on a set of wheels tires with half the weight.

A set of heavy wheels/tires in effect are like adding four huge flywheels, one at each corner. It takes LOTS of power to accelerate them and LOTS of brakes to stop them.