I have a 96 f-250 that I just bought so this is my first winter using it. Its been snowing so I have left the hubs locked for getting around town but when I took it on the freeway it didn't like going much about 60 in 2wd and it had like a rough humming going on. When I'd switch it to 4wd it seemed to run smoother at around 60-65. Anyone know what would cause this? Or if its normal with these trucks?