how to measure back space

[jprather]

is there an easy way to measure back space on rims that are not marked?

 

[Crackedback]

Lay a straight edge on the backside wheel lip and measure to mounting face.

Some manufacturers use the wheel lip, others use the bead surface, so the number change depending on method.

 

[hunt2elk]

Measure like Crackedback stated. This is how Crager measures them as I have ordered custom backspacing from them in the past.