Got the Jeep running great now, only problem is it hums quite badly anything over 60Km and has a slight vibration around 80-90 km and goes away right after 90. Does it with od on or off.

I'm thinking UJoints and tires as I bought it with crappy winter tires on it. Will check and replace U joints today or tomorrow as the probably have not been done before so doesn't hurt. Any tips on what else it could be?

Could be:
rear driveshaft joints
front driveshaft joints
tires
wheel/axle bearings

I'm betting that its the tires

_________________
U.S. Army Retired

Sorry to be clear the humming does not stop after 90, was just meaning that the vibration only occured between 80-90

Does it hum at a frequency that matches the speed of the tires turning, or does it hum at a much higher frequency, (about 3-4X as fast), indicating the problem lies in the drive shafts?

Just went and replaced the rear u joint it was toast. The vibration is gone but still the humming, I think it's the tires. I'll have to get some decent all seasons and hope that fixes the problem!