The 6 pot ones actually look a little slimmer due to the smaller pistons I guess. I wonder if there is a bit more clearance with those? Looking at philmeup post on another thread with his 6 pot with 18's, appears to be just over 1/2" of clearance to the inside of the rim which is all you would need in the radius to clear 17's depending on the wheel brand, offset and if a reverse rim or not. Would so love to know the centre of hub to outside of caliper on the 4 and 6 pot. Would make checking wheel clearance for anyone looking for a upgrade that much easier. Could measure these maybe while still mounted from the centre of cap to the outside of the caliper.