22.5” tires are a direct replacement for 20” tires, 22.5’s are tubeless so no dealing with split rims which many service people cannot or will not deal with. Just need to get proper wheels. Are your wheels Budd(stud centric) or hub centric. You will need to know that when searching for wheels. Nice truck.

Ed

'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.