Changing the
tire size from 265/75R16 to 305/75R16 will cause the speedo & odo to read about 7-1/2% low.
It’s worth keeping the load range designations in perspective. The “E” range for any given
tire just means it can be safely inflated to 80 psi, and the manufacturer certifies its load capacity at that pressure. Similarly, a “D” range designation is for load capacity @ 65 psi, and a “C” range is for load capacity @ 50 psi. A tire’s actual load capacity is based on a combination of size and the “load range” designation.
For example, a 235/85R16E is rated at 3,024 lbs @ 80 psi. The 265/75R16E, a larger
tire of essentially the same rolling radius and the same “load range”, is rated at 3415 lbs @ 80 psi. The 265/75R16D, a lightly larger
tire but with a lower “D” range rating, is rated at 3300 lbs @ 65 psi.
The point here is my suggestion that you determine your load requirements (separately weight the front and rear axles of your loaded truck), add a safety factor, and purchase the correct size and load range to meet your requirements and/or preferences. In addition to the “E” tires, you may find a broad range of styles, prices and availability in the “D” range that are suited to your GVWR.
