3mph might be too slow, not enough wheelspin makes you rely on your tires getting a perfect hold. Not saying it's not good for your application or is bad, but my Clod with dual Integy 55t motors and 9t pinions hits maybe 6mph, and it just barely has the wheelspin to get up stuff. Granted, it's still hard for it to get stuck, but if I were you, I'd go with the "high" range.