Backspacing confusion

I hope this is what you mean. Wheels can be purchased nowadays where the distance from the outer rim to the inner hub is different. This enables the vehicle to use wider tires without cutting the quarters or offsetting the leaf springs inward. However the dimensions are critical. Remember measure twice cut once.! I made the mistake of cutting my quarters 40 years ago...DUH... I hope this is what you are asking about. when in doubt GOOGLE it.. Good Luck