That is likely due to a poorly designed spacer. The distance from the back face to the countersink for the lug nut should be about in the same spot regardless of spacer thickness. To do it different is silly.You will need longer studs if your adapter is thicker than 1.25". I bought 1.5" adapters and the original studs were 1/4" too short. I've heard if you go less than 1.25", you'll need to grind the studs a bit.