Wheels are blocks in Trailmakers Engine to them to power them. You can also use wheels above and underwater, but engines wont be able to spin them unless the engine is above water.
Monster Truck Wheel
"Large and heavy wheel with good overall grip."
About
The largest of all wheels and by far the heaviest. The best wheel in terms of control in mud and offroad terrain, however, it is offset by the fact it will immensely slow a vehicle down due to the weight, friction, and poor aerodynamics.
Slim Wheel
"Relatively poor grip and speed, but very light weight."
About
A medium sized and thin wheel with atrociously bad control, especially in offroad terrain. Despite its description, it is by far the fastest wheel due to its light weight, aerodynamics, and lack of friction, making it excellent for vehicles that don't need to turn much on the ground (such as drag racers or planes that require runways).
Drag Racing Wheel
"Large wheel with better grip on tarmac than rough terrain."
About
An enormous wheel that's size is only surpassed by the Monster Truck Wheel. It has the best grip of all wheels on paved surfaces and thus does not easily come off the ground or lose control when turning on its intended surface. Despite its name, in terms of speed it's terrible, as it will slow a vehicle down due to the heavy weight and friction.
Truck Wheel
"Large wheel with good overall grip."
About
A large wheel that performs well on offroad terrain. Not nearly as large or heavy as the Monster Truck Wheel and thus, will not slow a vehicle down as much. While it performs better than most wheels in the mud, it will still suffer from some lack of control.
Spiked Wheel
"Good grip on rough terrain."
About
A medium sized wheel with spikes embedded into it. Has excellent grip in offroad terrain, keeping lighter vehicles grounded when driving offroad while only suffering a slight loss in speed compared to the offroad wheels. However, they still perform poorly in mud. An excellent replacement for the offroad wheels if you favor control over speed.
Motorcycle Wheel
"A rad wheel for your hog. Average grip on all surfaces."
About
A medium sized thin wheel with decent control. A very fast wheel that, unlike the Slim Wheel, has some measure of control. In comparison to dedicated offroad/tarmac wheels however, it's flighty and can easily lose control when turning.
Ski
"For gliding."
Other
It costs 20 complexity and is the most complexity expensive block
About
Not technically a wheel, but still placed under the category. It very easily slides across the ground. Unlike tires, it does not make use of an engine nor does it rotate, and so it requires another form of propulsion (such as a thruster) in order to make use of it.
