well i just saw a post that said somthing about 17 making a car go slower any one find this true? physically speaking how can this affect overall speed.

 

just on take off usualy do to them being heavier than say a 14'' rim. Plus tire diamter of 185 60 14 (stock Si 88-91 CRX) is about half a inch smaller than 205 40 17. In theory a 17 should give you more top end since it makes the trans turn lower rpms at higher speeds

 

17's weigh more because they are bigger, but the main problem is the inertial effects that happen by concentrating the weight of the rim and tire farther away from the rotating axis. This makes it harder for you to accelerate.