New answers tagged technic
Try this on for size: Here's an exploded view. http://www.brickshelf.com/gallery/ToaofTech/EV3LinearActuator/2015-03-29_11.18.53.jpg This should be compact, robust, let you change gear ratios (so you can get more speed or more torque; the linear actuators are very slow for most applications.), and mount to your system quite well. Cheers!
I personally have the Lego Group 62.4 x 20 S tires which came with the Lego Creator 7291 2-in-1 Motorcycle kit.
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