How to measure Outer Lip / Inner Barrel depths.
How to measure existing lips and barrels?
Once your wheels are split, you will need to measure from end to end the total depth of your rim lip. You will then need to deduct half an inch, which is the width of the bead. Once this has been deducted you have your final depth of your dish.
For example: If end to end your dish depth is 3", once you have taken away 0.5" (Width of the bead) you will be left with 2.5". This is the true way to measure your dishes.