Your average car is designed to drive on a paved road, and your average wheelchair is designed to roll across smooth surfaces. But just as 4x4 manufacturers design vehicles for alternate terrains, a host of inventors have begun wondering why wheelchairs oughtn't do the same. Handicapped folks, after all, do not live only in cities; and those in rural areas may not even have paved driveways.
A company called TC Mobility produces the Tank Chair, an off-road, all-weather wheelchair that "conquers streams, mud, snow, sand, and gravel, allowing you to get back to nature. Using rubber tracks and high-torque electric motors, TankChair will take you anywhere and back."
Here's Tank Chair inventor Brad Soden buzzing around on his other creation, the Speedster, which is made for less challenging terrain yet, as the name suggests, higher speeds: