I googled up standard barbell weight capacity and most responses on forums and articles say that standards are only rated for ~230 lbs. This one says 300 http://www.building-muscle101.com/weight-lifting-equipment.h... this guy says ~200 http://forum.bodybuilding.com/showthread.php?t=945996&pa...
Here it says 200 for 5ft http://www.bigfitness.com/noname8.html and 250 for 6ft http://www.bigfitness.com/weigbarbr6st1.html
It's a nightmare trying to find out the specs. I prefer a 5ft bar. Say I get more plates and this bar can't handle them, then I have to try other bars. I wish I could sell this weight set and get olympics. No worries about capacities there.