A picture of the very incomplete gantry as it currently is, to give a better idea of what I'm up to: < > The only other way to get wheels to turn is either roll them freely unbound to anything, or attach them to a rotor. You can adjust the suspension settings to make them ridged, and you can use vertically oriented suspensions to prevent side wobble as if it was on rails. Wheels lack any form of propulsion on their own. They also lack any form of innate rotation ability. They're just cylindrical objects, exactly as they are in the real world (try welding a wheel directly to something sometime and see how well it spins). You need to provide an axle to them, and propulsion should you require it as well.
Drive Medical Blue Streak Ultra-Lightweight Wheelchair With Flip-Backs Arms & Swing-Away Footrests

Your drive axle (brakes) always have to be on the ground... else you'll go down hill as soon after you've walked bow to stern inside the coach a few times...
Do you have a trike with a rigid frame, in other words, one that is not suspended? Are you getting tired of all those nasty road irregularities knocking you around and loosening the fillings in your teeth? Had enough torture for this lifetime? Want a posh and smile-producing experience? Well then, Loopwheels may offer a solution, according to their website. Essentially, with these wheels on a rigid trike, the trike is no longer rigid, that is to say, once installed in place of traditional spoked wheels, you now have full suspension in all three corners of your triangulated realm! Cool.