What is the Difference Between Offset and Backspacing on a Trailer Wheel

Question:

You talk about backspacing, but is off-set is the same thing? What is a positive off-set, and how is it measured? I have a wheel that measures 3/4 inch in further from the front to the bolt holes compared to the back. Is this the wheel I need?

asked by: Tom

Helpful Expert Reply:

Backspacing and offset are not the same thing. Offset is how much the mounting surface of the wheel is off of center. Backspacing is the distance from the mounting surface to the outer edge of the wheel closest to the trailer. So they are similar but not exactly the same thing.

A positive offset moves the wheel and tire closer to the trailer because the mounting surface will be further away from the trailer.

Dexstar wheel # AM20427 has a zero offset meaning that the mounting surface is in the dead center of the wheel. It sounds like the wheel you have has a negative offset (if the mounting surface is closer towards the trailer).

All of the wheels we have with a 5 on 5 bolt pattern have a zero off set. One way you can measure to determine for sure if the wheels have an offset is to take one off the trailer and lie it down flat on the ground or a table. Place a flat item like a yard stick or a level across the tire/wheel. Then measure from the mount surface to the bottom of the stick or level. Next flip the tire/wheel over and do the same thing. If there is no difference then it has a zero offset. If the back is a smaller measurement it has negative offset. If the front has a smaller measurement it has positive offset.

expert reply by: Michael H