There are many different factors as to the distances from the center of your router bit, for 1/24 I have my jig set for 5 1/2" and I have 3/4" rollers which give about 5 1/8" for a gutter on a straight. When using the jig on a curve as you move from a straight the outside gutter gets wider, how much depends on how far apart your rollers would be. The farther apart the wider the gutter becomes. My rollers are 9" apart and that gives you an extra 1/2" or so in larger curves for the gutter.
I would guess that the best way to figure out how much gutter you want is to take the longest car you are going to race, hold the guide pin straight along a straight edge or straight line running under your car and slide the rear of the car as far to the right as it goes and measure the distance from the guide pin line to the back of the cars farthest travel. That would insure you would not have a car hanging off the edge of your track.
Now I'm getting somewhere!I was making the track 2 feet wide, a 7 inch gutter on top of straight and 3.5 gutter at bottom of straight, 4 lanes with 4.5 between each.Is this too much?Need all the help I can get.Thanks Ron