He can run 10R22.5 on either 7.50 or 8.25 wheel. Another option would be a 295/275R22.5 which is about the same size as the 10R22.5 but much more plentiful.

Here is a chart Bridgestone puts out.

http://www.trucktires.com/bridgestone/us_eng/load/misc_pdf/minDualSpacing.pdf

If you read the note, the weight rating of the wheel is what is important. In order to gross 80,000 we have to gross 12k or more on the steering axle which means we have to run a tire and wheel rated at over 6k.