Here is a kit that lets you build cool off-road robots. The Mini Mantis 6WD Off-Road Rover has a bug-like chassis, 485 rpm Economy Gear Motors, and 4.3″ off-road tires. It has a bunch of mounting and customization options. With the 3.85” aluminum beams and 130 mm, oil-filled, aluminum shocks, your robot will be able to take on rough terrains.
The kit comes with 6 wheels, motor mounts, 6 gear motors, and everything you need to get started.