Just wondering how much of a loss in 1/8th and 1/4 mile times one could expect when going to an 18" wheel from a 17" wheel, assumming relatively same construction thus roughly a 6% weight increase. And then, would finding an 18" rim that weighed about the same give any difference in track performance, or less due to less sidewall to 'wrinkle'?

Reason behind this, I'm thinking of going with the Boyd Smoothie II's, I just don't want to spend 2 grand on something that's going to make my car slower, unless it's negligible.

Anybody know how much an 18" Smoothie II weighs? I think the stock 17" Bullit is 22.1 lbs.

Thanks in advance.

 

You also have to take into account that the tire will weigh a little less if it's the same overall height. I went from 17's to 20's on mine and the overall package only weighed about 3 lbs. more. Aftermarket wheels can vary greatly in weight though and most Boyd's i've seen are relatively light, especially if they're two-piece. I can't tell a difference and I don't think you will either with just 18". If you go to a larger tire you may tell a difference though.