If you have the right design wedge, you don't need anything higher than that. No need to beat up your hydraulics if you don't need to. Mine is set at 2300. I could go higher, but a few hundred psi isn't going to push through a piece that's stuck, so I leave it low. I know 2300 won't damage anything either. If it's going through pieces good, I wouldn't touch it.2250 is pretty low for max pressure. Is your pump just a single stage? If you have enough motor and the splitter can handle the tonnage, I'd set it to closer to 2800-2900.
If your running in temps like that most of the time, I'd go with a thicker oil, like AW46 if your using 32.