Is it possible to change the pressures in the tires for load/no-load conditions without upsetting the tire pressure monitoring system on the 2006 Tundras? My parents have one and it seems like the rear tires have to be pumped up too much for no-load driving. It makes the rear seem especially harsh. They would like to run the same or less pressure in the rear if that's possible. How do you reset the system for a desired air pressure?