I've installed the remote tire pressure monitors on my '09 FLHR. (I don't want to take any grief about the value. I also have the digital oil temp/dipstick and I check oil pressure, oil temp, tire pressure before and after every ride. It just makes it easy!!) Anyway, back to my observation. I inflate the tires to 36psi F and 40psi R per the specifications. At the beginning of a ride today the temperature on each tire read 65F. After a long ride, the front tire reads 37.5 psi and 70F, a 1.5psi increase. The rear tire reads 47 psi and 90F, a 7 psi increase due to the greatly increased temperature, presumably because of proximity to the exhaust. Obviously the relative difference in pressure between front and rear is not constant over the course of a ride.