18 inch rims on a 3C2?

[SiH]

I'd like to fit 18 inch rims on my 3c2 eventually,with dumper/ agri tyres on them. Are these rims difficult to get hold of? As i rarely see them on the net? Is there any other machine that has rims the same or similar? - Ive seen some farm trailer rims that look like they might do? Is there any drawbacks in putting the larger rims on?
Also, I have a set of crane/ hiab pallet forks, that I want to use on the front loader. I know I could dangle them on a chain from the loader, but I'd like to get some brackets to weld onto them,with the aim of being able to put the forks on inplace of the bucket. Can these bucket ears/ brackets be bought off the shelf to fit a 3c2? Or Should I make some up? I wont spend silly money, as I dont have it, but it would be damn useful to me!