Answer:
The tyres are usually 22.5 or 24.5 (with owner/operators being more prone to using the 24.5s than company fleets), and your low profile tractors will run 19.5 tyres. I can't say what the rim dimensions are for the low profile tyres, but your 22.5s and 24.5s are typically 11R22.5/11R24.5.