I used to take industrial grinding wheels from the big shop to Mach-B grinding wheel service on Groesbeck in Warrem Mi..now they are out west someplace.
They used a disk that would roll and cush the wheel to the needed size..the soft steel disk looked like a 3" cup wheel.(might have been 2")
Yes they had to be ring and speed tested, and marked so because workers would be involved using them..Never did a wheel test bad or crack doing this.
I asked about diamond dressing and ..(I forgot his name) said this method was lower cost..
*Good to diamond wet dress a few and see if the time and diamond use made it profitable, with turning the diamond after about a half hour use.
Might consider selling the big wheels or trading them for correct size.
50 bucks that is a good price for a big wheel.
There is a story about how that shop got started but none of my bees wax to tell.
Found their site good still in business. likely cost to much to ship but if you do tell them Buck said Hi.
Mach-B Grinding Wheel Shaping & Resizing
We had a box of wheels that would blow at markes speed from a big name wheel maker..called them up and they replaced to box of wheels , then recalled that run number..nobody got hurt, so it was not a big deal. lucky we were one of the first to recieve that run number. likely cost the manufacturer big bucks to recall and scrap a run number. No I wont tell the name.
*That is another good reason for safety glasses and wheel guards...and not to be in the blow zone when starting a wheel..like when Od and TC greinding.. good to stand off side.
(Some think we should out law cars because people still get run over.}Many shops want to out law manual grinders because they dont understand OSHA rules..much because the ones in charge are not grinder hands..likely not even machine hands. Go figure>
oops I have a job to do..