You may realize this, but a 5 mm difference is a difference of 0.2" on the same width wheel (not 1.57").
In order to compare poke you need both the width and offset of the wheel. Two wheels of different width can have different offsets, but the same poke. For example, an 8" wheel with an offset of +40 would have the same poke as a 7" wheel with an offset of +28 (but, the 8" wheel would also be a full inch closer to the suspension). Here's an easy online calculator for comparison:
Will They Fit
