Wheels

Wheel Basics 
REV Robotics offers three types of wheels: Traction, Omni, and Mecanum (REV-45-1655). There are two different traction wheels available: the standard Traction Wheel and the Grip Wheel (REV-41-1267).  The traction wheels resemble standard wheels, like what you might see on a car or a bike. The main focus of the traction wheels is to pull a robot (or create traction) in a forward/backwards motion. 
Omni and Mecanum wheels, however, are omnidirectional wheels. Omnidirectional wheels give additional flexibility to a drive train by adding an additional vector of motion, known as strafing. 
This section will walk through the different kind of wheels available through REV and best practices for utilizing them. 
Traction Wheels 
The Traction Wheel comes in three different sizes to allow flexibility in design and usage of the wheels. 
Product Specs: 
Hub Material: Nylon (PA66)
Tread Material: TPU
Width: 15mm
Hole Diameter: M3 clearance
Hole Spacing: 8mm
Weight: Various weights ​
Grip Wheels 
Grip Wheels are wider than standard Traction Wheels, offering traction while still being lightweight in specific drivetrain applications, like driving on soft foam tiles. These wheels are designed for optimal grip in situations where the material the wheel is interacting with is compliant like soft foam tiles, carpet, or foam balls.
Product Specs:
Diameter: 90mm
Width: 25mm
Hub Material: Nylon (PA66)
Hub Bore: 5mm Hex
Tread Material: TPU
Tread Durometer: 65A
Hole Diameter: M3 Clearance
Hole Spacing: 8mm
Weight (single wheel): 88g (3.10oz)
Omni Wheels 
Omni wheels are a special kind of wheel that has smaller rollers around the circumference of the wheel. These rollers can passively roll perpendicularly to the direction the wheel is driven. This wheel makes it easier for a robot to turn in a differential drivetrain. Using Omni wheels in conjunction with each other can create more maneuverable robots in advanced drivetrain applications.
A single omni wheel is the same thickness, 15mm, as all other motion components. In some applications, it might be desirable to stack two omni wheels, with one rotated by 60° from the other, as shown below. By setting your wheels in this configuration you ensure that a roller is always in contact with the ground. This results in smoother and more consistent operation.
Product Specs:
Hub Material: Nylon (PA66)
Roller Material: TPU
Thickness: 15mm
Hole Diameter: M3 clearance
Hole Spacing: 8mm
Weight (single wheel): Various Weights ​
Mecanum Wheels
‌REV Mecanum Wheels have a similar functionality to the Omni Wheel. The Mecanum Wheels have rollers around the whole circumference of the steel plate rim, set at a 45° angle. The full set of rollers present on the Mecanum Wheel remove the need to stack two wheels together like is required with the omni wheel.‌
Tested for the rigors of competition, REV Mecanum Wheels are steel plates with rollers supported by ball bearings allowing for the perfect combination of wheel rigidity and roller movement. Included in the set of wheels are Universal Hex Adapter making mounting to 5mm hex shaft easy. With a 75mm diameter these wheels allow for a lower profile giving more space for building mechanisms and space for game elements.‌
Product Specs:
Hub Material: Steel
Roller Material: NBR
Diameter: 75mm
Width: 40mm
Weight (single wheel without Universal Hex Adapter): 179 g (0.395 lbs)
When using mecanum wheels it is important to orient them correctly for optimal performance.