Alright, I've a hack this thread reminds me of. Are there extra points if a thread hack and a work trick coincide?
Tony's 'bushed washer' for bench or pedestal grinders seems related, to an odd surface grinder application.
Lots of surface grinders carry 1.25 [31.75mm] ID wheels. Generally the wheel shroud/ guarding indicate largest wheel diameter, zillions are 6", 7" and 8". Average surface grinders, 5" x 10", 6" x 12", 6" x 18" use them, and lots of cutter grinders can. If you examine wheel catalogs, their prevalence is clear. . .

Between ticket work, I'm trying to get their shop more operative. Let's just call it a Herculean task. Like horizontal mill I've run, until riggers dropped it about 20 inches. . .but wait; there's more!
You know when someone thinks out loud? I'm writing the same way, working out day-end events. Follow along while I ramble.
For a reason I have no explanation, what look like comparable sized machines still have 1.25 arbors; inside a 12" shroud! Puzzled, I've looked for 1.25 x 12 wheels, knowing they'd be rarer than hen teeth. Yeppers, none found.
Examined the machine further, this case happens to be an auto-feed Thompson, cast iron everything. Even the base, with cast-in baffled coolant reservoir. Tag indicates a single voltage motor, but capable two different RPM 1500 and 3000, by switching leads [not direction, or change 220/440, RPM only]. Smaller wheels, higher RPM's. Bigger wheels, lower RPM, increased diameter creates the effective FPM [Feet Per Minute].
Our wheel storage is all 6 inchers, and one 8, still 1.25 bore. In a box of grinder stuff [I found], a weird looking bushing [I think] like Tony's but slightly different [I guess] for the 'front' of the wheel. 12" wheels are 3" bore. This spacer [steel] is 3 plus, maybe someone didn't finish it. I have to look, yes spindle is 1.25, but outer washer is larger than a 6", 7" or 8" would use, probably spindle flange is too? Checking that tomorrow.
Getting this machine on line's a benefit, especially with the 18 or 20 inch magnet.