Before Ural put a weight limit on the new bike I had my Retro loaded down with Wife and camping gear and rode it over the Truck Scales in Oregon. It registered 1800 lbs. That's 1000 lbs or 1/2 more then the weight of the empty rig. So I wouldn't worry about your 275 lbs.
'78 BMW R100/Ural sidecar, '99 Ural Patrol
'03 BMW R1200CLC Solo & Ural sidecar Rig
'06 Honda Big Ruckus Solo & Sidecar Rig,
'08 Ural Retro, '10 Ural ST Solo