If you will be racing in a Royal Ranger Pinewood Derby, or will be using a pinewood derby kit from S&W crafts, then you will likely be interested in the article posted at:
www.maximum-velocity.com/royal_ranger_pinewood.htm
The article provides some good information on wheel alignment for kits which use the 'dowel and screw' axle system.
Royal Ranger/S&W Kit Wheel Alignment
Moderator: MaxV