An Inside Look At Segway's Technology
"The p-series is designed for "dense" urban environments, where crowds of people make cars an inconvenience. The wheelbase is tighter21 inches versus the 25 inches used for the industrial modeland the wheels are smaller, only 14 inches. Legally, the Segway is not a motor vehicle and can run on sidewalks at speeds up to 12.5 mph for the industrial model and 10 mph for the personal model."
Thanks to Michael J. Miller