I'd have to go outside to look to be sure (and it's cold as heck up here so I'm not up for that tonight but I think it's 300 max. If it's only 120 then I was really pushing the limit, huh? But yeah, I drove from Georgia to DC, then from DC to WA with about 500-600 lbs worth of stuff up there. No problems whatsoever.

I made sure I packed the stuff so it was sort of aerodynamic - the stuff in the front was packed a little lower than the stuff towards the back - but I don't imagine that had a huge impact.