Wheels, Tires, Axles
Your Connection to the Ground
As we said, if you're going to do some heavy duty off road driving, you may be happy down the line if you don't use threaded axles. Or, if you do, use bushings to ensure that no thread is exposed when the wheels are secured.
But you can also use special pivoting retainers and forgo the threads. Make your own retainers by welding an L-shape of 1/4-in. rod to one face of a washer large enough to slip onto the axle you've chosen. The tail of the L enters a hole in the plate, holding the axle in place in the notch. (The hub nut shown on the front axle is an alternate treatment.)
The defining feature of this design is the enormous rear wheel. The 12-by-16 ATV type has no tube and is kept at only 12 lbs. pressure. At such low pressure, the tire can cups itself around small boulders and logs in the path, smoothing your ride. Also, with the design's 8" ground clearance, you won't get stopped by small obstructions nearly as often.
With such a large and low pressure tire, it's virtually impossible to spin out loose soil or mud, or on ice. It floats along on top of sand, making this trail-blazer a practical beach buggy as well.
The design calls for a 6-by-6 snow-and-mud tread tire on the front; you keep its tube at 15-20 lbs. pressure.
Check your parts supplier for what they offer, and their selection of material for the wheels (aluminum or steel).