How many spokes are in this wheel? I had major issues with machine built 28 spoke wheels that came stock on my hybrid a few years ago. I upgraded to hand built 32 spoke wheels and they have been solid for more than 10,000km with 100kg loads.
Is this your bike?
http://redlinebicycles.com/bikes/2014-metro-classic/
Those wheels are probably machine built and are not capable of carrying a lot of excess weight, I would build up a set of heavy duty 36 spoke wheels for peace of mind if nothing else.