Tires of same size with higher ratings require higher pressures to get that increased capacity. There are load charts available. Usually the D will carry the same amount at the C's pressure, but not every time. So check that the wheel and valve can take the pressure the D tire needs. Or run the D's a little higher than the C's for a safety margin.
Don't get D's and run them like C's. That just creates more heat and rolling resistance due to pulling the sturdier tires along.
If you go all the way to the max pressure you add the capacity and give back some brake and corner traction from your slightly smaller contact patch...of course nobody corners a trailer enough to slide. Only folks having an emergency.
2WD Ranger wheels are zero offset, so no issue with that. Trailer wheels and hubs in our sizes all use the same zero offset 5 lug 4.5" bolt circle, its a standard item. In the trade it's called "5 on 4 and a half". You will see it printed as 5:4.5"
Boat trailer tires are sometimes near capacity and need full inflation. But every travel trailer I have seen does that. They are notoriously cheap in that business.
To see you trailer's capacity and recommended pressures and tire size look on the left, oops port, side of the tongue, there will be a placard.
