Replying to Fks 18 mounting question

Are the bolt patterns on the 14 and 18 the same? Just got a pair of 18s and i wanna put them on a pair of RMUs that have 14s on them, i was wondering if remounting them would be any problem, if i could use the same holes, or will they need to be redrilled. Also they are mounted center currently and i was wondering if this would pose any problems mounting them center again, for the same boot size, just with the 18s instead. +k for actual help