#8768, "RE: will bigger wheels always make you slower, and other ?" In response to In response to 12
Larger diameter wheels will reduce your final drive ratio and make your car a bit slower but I'd think a 1% difference is not going to make that much of a difference at all. Also, heavier rims and tires will make your car slower, but this is what slows you down the most: rotational inertia
It takes energy, work, power, whatever to get a wheel to turn. The more weight on the outside diameter of an object that rotates, the more energy it takes to get it to spin.
Simple experiment. Sit in a chair that spins around. Put two 5 lbs weights in your lap. Spin around while sticking your arms out, it doesn't take much effort to get you to spin. Then, hold the 5 lbs weights in each hand and do the same thing. It takes more effort to get you to spin at the same speed.
The outer diameter of rotation (your hands) remained the same, but you put the weight that was in the center of rotation (the weights on your lap) to the outer edge of rotation (your hands).
What's that got to do with tires? Well, a 225 tire will take more effort to spin than a 195 tire. Yes, lighter wheels and tires are good (less unsprung mass, and less weight is always easier to move around than more wieght) but where that weight is makes the difference. Wide, heavy treaded tires will slow down a car with no power (i.e. my car and our cars) more noticeably than a car with more power.
