One of the bikes I picked up came with Wolber Profil 18 rims (super light 310-330 gram rims). After a bit of digging around I noticed that they were usually found on time-trial or specialty bikes. I have two questions about them:

1) What size tires are most appropriate on them? Do I have to buy 18mm tires? Can I go a little wider? What are my options (sorry if this sound dumb)?

2) Are these rims ok to ride on streets that aren't smooth as a track? Are they safe for taking out on a spin and using for training or would you really only use them for special occasions?

Guy