45 is probably way on high side. Is that hot or cold? You know the tire heats up and will raise the pressure? so when you are at 45 and it heats up it could be as high as 55 or more possibly exceeding the air pressure requirements. you should do air pressure by hot and cold and no than 10% difference and load for HWY driving. Too high a pressure and you hit something the tire can burst.
Beater probably has a lot of good info for thread.
See you on the trail
Couple o' FJ40's, BJ70, PZJ77, UZJ100, TDI