I just finished a 4500 mile trip on my K1600GT and carried two digital gauges that I have been using for a few years. When I checked the tires one morning, both gauges showed psi as 16 pounds low. I put in 16 pounds and went on my way. Thereafter, I was seeing a warning sign and pressure was showing as 16 psi high. Checked the air pressure several more times and it was reading 42 psi, as book recommends.
After arriving home I checked the tires with a third digital gauge and it showed the psi as 16 pounds too high. Used one of the trip gauges again and it showed 42. I threw one of the gauges away and replaced the battery in another and now both show the psi is 16 pounds too high. Needless to say, I feel lucky running 16 psi too high for 2000 miles in hot weather. I would never have imagined 2 gauges would both be faulty and give a wrong reading rather than not show anything when psi is too low or high. Lesson learned.