Brakes, yes. Rims- I don't know? Is there any way to tell besides just trying to cram it on there?

I have Sun MZ-14 rims. I believe that this is it: http://www.amazon.com/Alloy-MZ-14-70.../dp/B000WYCJ80.

It states the following: "700C 32-Hole 420-gauge Silver Anodized 622x18"

That is all greek to me. Can you point me to a resource that tells me how fat of a tire I can cram onto my rim? Clearance does not seem to be a problem otherwise.