I did my first mod to increase the speed on one car and followed the directions from the main part of the site.
I took the wheels off of a FTE Fast Fish and added them along with weight to 2008 Dodge Challenger. I noticed that the wheels from the Charger are too narrow for the Fast Fish body and the wheels seem to be too wide for the Charger as there is too much side to side play and it slows it down---but it is still faster.
I assume there is no way to fix this except find wheels that are also the same size both in length and circumfrance? If so, is there an easy way to figure out which wheels will work before you tear apart a car---is it just eyeballing it?