A higher load range within the same tire size means a higher ply rating which also means a higher capacity. The Karrier ST205/75R14 Radial Trailer Tire - Load Range C # AM10234 has a maximum load of 1,925 lbs at 60 psi. The Karrier ST205/75R14 Radial Trailer Tire - Load Range D # AM10235 has a max load of 2,200 lbs at 75 psi. The tire dimensions are the same so you can certainly upgrade from a C to a D. This will also mean your tires run a little cooler so they will last longer. view full answer...