When a P-metric or metric tire is installed on a light truck (SUV, pickup, minivan), the load capacity of the tire is reduced by a factor of 1.101 as prescribed by the Federal Motor Vehicle Safety Standards (FMVSS). For example, 305/50R20 has a maximum load capacity of 3086 lbs. If this tire is fitted to a light truck, then the actual allowable load capacity for the tire is 2805 lbs. (3086 lbs. divided by 1.1). If you replace the original tires with the exact same type (P-metric, hard metric, LT-metric, or flotation), size designations, and ply as the tires that were originally installed, just follow the vehicle’s tire information placard for proper inflation pressures. If, however, you apply a ‘Plus zero’ or plus-1, etc., fitment to a light truck, you must discount the replacement tire’s load by the 1.10 factor and ensure that the replacement tire has sufficient load capacity by inflation to support the load of the originally installed tires.
