how do you get the roll out ? i know its tire spur pinon and pie but in what order?

thanks

tire times pie times pinion divided by spur

tire diameter x 3.14 ÷ gear ratio = rollout
(spur/pinion)

Go to www.ycityhobby.com Look under menu r/c goodies and download a rollout calculator

If you have Excel or Excel viewer I'll send you a chart for whatever spur gear you use and a variety of pinions.
Let me know if this helps............