Anatomy Of A Trailer Wheel

The trailer wheel isn't thought of to be as a 'technical' piece of equipment all the time. While it's functionality is pretty straight forward, there are many critical parts of the wheel that are often overlooked when considering the best option for your application. See below for 'the anatomy of a trailer wheel'.

  • Wheel Width - The inside distance between the bead seat faces, note that this is not an overall width measurement. 
  • Wheel Diameter - Diameter of the cylindrical surface on which the tire bead rides, again note that this is not an overall diameter measurement.
  • Wheel Offset - The distance between the wheel center line and the mounting pad.
  • Backspace - The distance between the mounting pad and the outer most part of the wheel's drum side.
  • Wheel Center line - The absolute center of the wheel.
  • Bolt Circle Diameter - The diameter of the bolt-holes.
  • Wheel Diameter - The wheel's diameter where the tire's bead mounts and creates a seal.
  • Mounting Pad - The portion of the wheel that butts up against the hub face.
  • Drum Side - The side of the wheel facing the trailer drum.
  • Street Side - The visible side of the wheel when mounted correctly.

The offset of the trailer wheel often is the difference between the wheel working/not working on your trailer. Some wheels are designed to give more space for the trailer's hub. Below is an explanation of the difference between a 'Positive' and 'Negative' offset.

  • Positive Offset - The wheel's mounting pad is adjusted away from the drum/brake side of the wheel's center line.
  • Zero Offset - The wheels mounting pad is in line with the wheel's center line.
  • Negative Offset - The wheel's mounting pad is adjusted away from the street/wheel side of the wheel's center line.

The above information can be vital when choosing the correct wheel for your application. Be sure to verify your measurements before you proceed in the replacement of your wheels.

Please feel free to contact us with any comments, suggestions, or questions.