28 to 24mm is a reduction of 0.158", just a tick over 1/8 inch. I did put a OEM bolt and a 24mm though the Rotec and there was plenty of thread sticking out the back. If you really want to be sure
pull an OEM rim off and stick an OEM bolt into it and measure how much thread length is protruding.
Then do the same with the Rotec and new bolt. Let me know what you come up with. My OEM rims are still at DT because the wouldn't fit in the car.