More interesting, I think is that going up a wheel size (even if it's the SAME weight) increases rotational inertia 7-8%, the same as adding ~1.5lbs per wheel or ~12lbs total equiv chassis weight. Again, that's assuming the exact same wheel weight, just a different size. The bigger your wheels, the more that weight hurts. For fun, figure out what a 19x8" wheel (forged 19's come in around 27lbs) would do compared to a 17x8 (forged comes in around 14lbs).
I'll save ya the trouble- it's like adding 10% (over 300lbs) of weight to the chassis. Ouch!
For more fun, let's assume somebody has a Mazda Miata with the factory 14" wheels weighing 10.4lbs. Yes, those are the factory wheels from the mid-late 90's. Joe Somebody removes them and fits 18's. Of course, they're chromed, which adds even more weight. Wheel weight is now a whopping 30lbs per wheel, not uncommon for chrome wheels. The tires only weigh marginally less on the larger wheel. The equivalent static chassis weight is roughly 600lbs, more than 25% of the car's curb weight. Imagine your new tire combination adding 2 whole seconds to your 0-60 time- you're now as fast as the Toyota Prius. Wow. Your car feels like a 3000lb family sedan. No wonder Miata guys are finatical about keeping small, light wheels on their cars. Recent Miatas have come with heavy 17" wheels, and the owners swap them out for lighter 15's.
