I agree with tangofox that larger tires should have lower pressure. Some folks see the max pressure value on the tire and mistakenly believe that that is a recommendation, rather than the do not exceed pressure. A few years back I had a new set of tires installed on a Bronco. When I drove home I was alarmed by how twitchy the truck was. I thought I had made a major mistake in the tires I had selected. I checked the tire pressure and found they all had 45 psi in them. I dropped them all to 30, and it drove like a new truck.

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'97 E 300 D