Does a rim upgrade equal brake, suspension upgrade?

I have a 2004 isuzu rodeo with the stock 16" alloy wheels and I am looking into getting some custom rims. With that said, I have heard of folks having to upgrade a lot of other things on their vehicles once they get rims. Just wondering what else would I need to change (brakes, suspension, etc)? I know that 22s will fit with low profile tires, but probably realistically leaning toward 20s with a little more tire. I have the money to get the wheels and tires I want, but just curious about other expenses....any help greatly appreciated.