trailer bearings

[Brockport Bill]

i have had problems over the years with trailer bearings getting hot -- Its a double/tandem "American" brand trailer 13 years old bought new from a seadoo dealer-- well maintained. Just recently burned up one bearing even tho i had greased it with marine grease at start of trip. So i just had a dealer replace with a new axle and bearings etc. Left the dealer and drove home -- 65 mph on interstate. After about 25 miles the hub housings were very hot to the touch. Removed the rubber outer gasket and could see the blue grease -- however the entire trip home 120 miles the outer hub was significantly hot to the touch meaning the inner bearing must have been hot to make the outer casing hub that hot. To me this should not be happening. Any ideas why brand new bearings would make the outer hub housing so hot to the touch? thanks