I'm looking to get some Work Meister wheels for an aggressive setup. If I were to get a 19X11 in the rear with these three offsets below, are my calculation for their correspondence lip measurements correct, or are there other factors I would need to consider? I'm still deciding what's the best offset/LIP combination and need these number for reference.

Offset(mm) ----------- Lip meas. (in)
0 ----------------- 5.5
+5 ---------------- 5.25
+10 -------------- 5.0

 

I think your calculation is pretty close.

5.5" = ~139.7mm which is half of 11" (~279.4mm) so a +0 offset makes sense.
5.25" = ~133.35 mm (139.7 - 133.35 = ~6.35) so offset around +6.
5.0" = ~127 mm (139.7 - 127 = ~12.7) so offset around +13.