bluetoad7

My 06 HR Scepter 42 came with 295/80R-22.5 Goodyear G70 tires.  Due to the weight on my front axle I have replaced the steer and tag axle tires with 315/80R-22.5 Michelins (which Acuride Wheels says are acceptable for use on my rims and were $50 cheaper apiece).  The reason for doing the tag as well is to have a spare for the steer axle if an emergency arises and no 315 is a available.  That being said, the most common and least expensive tire replacement is the class 8 trucking industry standard 11R-22.5, which is the SAE equivalent of the 295/80R-22.5 (a P-Metric size listing).  The tire diameter is the same for each.  So, my current drive axle tires are 11R-22.5 Dunlop all position tires.  They have not affected my speedometer accuracy, which 295/75-22.5s will likely do in your application due to different tire diameters.  

Looking at your control board pic, I would suspect issues with the printed circuit board might be the problem .  I had issues with a smart wheel on a friends Diplomat and nothing made sense.  All operations were erratic.  Had been to three different techs over time with no success.  Opened the front run bay and saw that someone had removed wiring or such from the bay and left it open to the wheel so road debris had entered the bay.  Pulled the printed circuit board off the wall and  the back of the board was coated with road film.  Cleaned it up with dielectric spray and all issues disappeared.  There must have been cross talking going on between circuits.