With all due respect to your mechanic - he is an idiot. He needs to check the load/inflation pressure tables for your tires. Even at 26 psi, the tires are rated to carry a greater load than the vehicles axles. If you have the original size and type of tires listed on the tire placard, then you should go with the vehicle manufacturer's recommendation (as amended to 30 psi). Adding a few extra psi is OK if you are going for a firmer ride, but adding an extra 10 psi is ridiculous (assuming you have the OE size and type of tire). The original 26 psi recommendation for Explorers with the optional size tire was done for SAFETY reasons, not to improve the ride. Ford found that with higher inflation pressures, the original style of Explorer reacted to quickly to steering inputs and was relatively easy to get sideways when making violent maneuvers, which could lead to a rollover. By dropping the tire pressures to 26 psi, the response to steering inputs was dampened. Unfortunately, Firestone sold Ford tires that were not up to industry standards and had a tendency to fail dramatically. Raising the pressure to
30 psi reduced the heat build up and lessened the chances of a tire failure. However, it didn't fix the tires, it just masked the defect. In 1996 half of the Explorers got Goodyear tires. These tires had the same pressure recommendation and there was no problem with dramatic failure (I actually owned a 1996 Explorer with Goodyears - never had a problem). My Father had a Ranger with the crappy Firestone tries (same as on an Explorer). Rangers had a slightly higher pressure recommendation. In less than 15,000 miles, my Father had 3 of the 4 OE Firestone tires fail. They did not have the belts separate. In his case the tread literally split in the center. We drove the truck on gravel roads regularly, and the tires were so crummy they couldn't stand rock bruising.Do you have "P" series or "LT" series tires installed on your vehicle? If they are "P"series extra load tires then the tires are not actually rated to carry any more at 50 psi than at 36 psi. The higher pressure limit is intended to allow for higher pressure recommendation by the vehicle manufacturer for high speed driving. If you are running "LT" tires, you are doing something Ford specifically warns against. LT tires need to have higher pressures to achieve the same load carrying capacity as "P" series tires. This is because "LT" tires have thicker sidewalls and carcasses. Because of the thicker sidewalls, "LT" tires suffer from greater heat build up at high speed. The higher pressure is needed to reduce flexing and reduce heat build up.
Ed