I'm no expert, butt you most likely will not just need wider wheels, you will have to know what off set is needed for clearance,
if you don't get correct offset you could end up with things rubbing! as just wider wheels don't mean they will be a working combination!
because if you go from 10x16.5 to 12x16.5, you might also run into tire clearance issues in general(too tall wide)
as the 12x16.5 will be about 3 inches taller and 2 inches wider
going to larger tires will also effect stress on parts
if your wanting to go to the 12's for more ground clearance, your only going to gain an inch and a half is that, which I really don't think is worth the hassle and costs to do so
if more traction or flotation is what your after, you might be better off going with over the tire tracks, which will gain you both in a noticeable way, but even with this, you may need to get spacers to not have rubbing/clearance issues
and tracks will also add more stress to machine
there is no way of getting past this with either however! how machine gets used with them and the operator using it will have more impact on how hard the new set up can be on things
adding bigger tires/tracks, can some times find the weak link and lead to repairs, HAHA!
food for thought!