wheel width vs. tire width, and rust

[boondocksaint]

is there a common ratio for picking the best widths for a tire/wheel combination?

the tires i'm looking at are 1.75" wide, with the wheels just under an inch wide. I'm presuming these will work, but are there any advantages/disadvantages to going wider/smaller?

also, how badly do steel wheels rust? i'm considering the black rc4wd pro10's, and the truck will see more than its fair share of mud. will this become a problem?

Thanks.