When to service wheel bearings?

[JeepGuy-FUN]

i just had a ulitilty trailers wheel bearing fail on the highway this weekend and i had to leave it and when i came back to get it the next day it was stolen, so it got me thinking when should i service the eheel bearings on the camper

 

[keyser soze]

From On-Line resources, travel trailer and fifth wheel TV wheel bearings should be lubricated every 12 months or 12,000 miles.