jimbeater
+1y
they are meant to hold the stock rim on exactly center... i have heard some vehicles are hub centric (centered, and weight is mostly on the hub, not the lugs), and some are lug centric (wheel centered, and weight is taken by the lug nuts)...
my Z71 4x4 rims (the usual old skewl style you see, from a 95ish truck i think?), did not need any machining, and all tabs are still on my truck (92 b2200)... i have not tried to fit these on my 88 b2600 4x4 truck...