Mine actually calls for 265s according to the door label, but due to cost and availability I retired to 235, which is basically 7% less in mileage and revolution per mile, which really wasn't that large a factor far as I'm concerned. Lt hasn't come close to dragging but I don't go out looking for large rocks to climb anyway
What does the 410 change in revolution per mile?
Is it actually a lower gear?
It seems your mixing some information that makes things confusing. You're looking at tire revolutions per mile where "RPM" and gearing is relating to the overall engine speed.
Given the same tire size (my truck also calls for 265/75r15 on the placard) but different gearing, the engine will spin faster with the higher number....equaling more power transferred to the wheels.
This chart shows a truck with a 265/75r15 tire and the difference of engine RPM using 3.73 vs 4.10 gearing with the 5R55E transmission. At 60mph in 5th gear, using 3.73, the engine spins at 1840 RPM. With 4.10 gearing, its at 2023 RPM....a 183 RPM difference. Although the engine RPM is higher with the 4.10, it also is working with less resistance so it move the truck easier than if it had the 3.73.
Switching to a smaller tire, does a similar thing.
Below, the chart uses the same 4.10 gearing for both tires but the tires area 265/75r15 and 235/75r15. With the larger tires, the engine spins at a lower RPM than with the smaller 235 tires.