I just bought 12mm slip on hub centric wheel spacers. Do I need extended wheel bolts?

 

yes.........

 

ABSOLUTELY you need longer studs to match the spacer, this is why wheel spacers have such a bad reputation, because people put themselves in an incredibly dangerous situation. The proper number of turns for a 12-1.25 is 10 turns for flush engagement, ideally you would want about a 3 thread reveal. I have 13 turns on my wheel spacers in the front and 12 in the back but I would never run LESS than a flush reveal (amount of threads sticking out past the nut of width same as thread diameter)

 

jus get 15mm spacers with the studs already there dont need to worry about extended studs

 

^this is correct.

Or I have some 10mm ones that are hubcentric and v2 with built in studs if you wanna buy them off me. Always easier to just go with spacers that have built in studs; just make sure to follow TQ specs when tightening lugs.