"These pants are too big."
Translation:Ce pantalon est trop grand.
I know this is a copy-pasted answer but I figured it might help you too: I was under the impression that it meant more like "thick", in the sense that the material is too heavy. So still quite offensive about a person, but not "wide" when referring to objects. Correct me if I'm wrong!
I read on one of these forums that 'grand' is used when something gets bigger by getting taller whereas 'gros' is used when something gets bigger by getting wider. I'm English and if I said 'these pants are too big', I would be meaning that they are too wide, not that they are too long. For that I would say 'these pants are too long'. So I think gros should be accepted here.