there are some tabs on the hub that lines the wheel up center on the hub you have to grind them off cuase the center hole is smaller on chevy wheels then on mazdas but if you do that you will not have anything lining the wheels up but the lugs which i think you need to get special ones as well or you can leave the tabs and have the wheels center hold made bigger but that will make the metal between the center hole and lug holes thin both ways have been done
got mine bored out, the bore size is 93 mm on a mazda....chevy wheels are smaller, so get it bored to 93mm
you can get away with grinding the tabs down with chevy wheels, just get lobed lug nuts....but when you ever have to put those stockers back in, they will not line up, because they rely on those tabs you grinded off to keep centered
certain chevy wheels you can get away with just boring the middle...i had to get some metal shaved off the back face so it'll tuck in better, got 1/8th shaved off, my wheels barely tuck with a rolled fender lip