Was that pressure range of 50-52psi hot or cold? Cold they should be 32psi or so (can't recall the exact numbers off the top of my head) and I seriously doubt they'd gain 20psi under normal driving conditions. You'll end up with premature wear down the center of the tires at those pressures, handling will be compromised, the ride will be harsh but the fuel economy will improve. Check the driver's door jamb for proper cold inflation pressures and set all tires per that label when cold.