A 30mm tire on an Alex R500 rim is nearing the recommended max, but isn't a safety issue. It does mean however that you may have problems getting tire to seat evenly around the rim channel; if this is the problem you will notice the tread of the tire has a considerable wobble from side to side when you spin the tire. When I run into this problem I usually go to a plastic rim strip (Velox makes a good one), which is slicker and thinner so the cord can slide into the channel easier; baby powder or soapy water may also work if you don't have a cloth rim strip.