I just measured the inner width of my rim with a ruler and it seemed to be a hair over 14mm. Looking at the tire sizing chart on Sheldon Brown's site it doesn't have an entry for 14mm inner width rims. My wheels are Vuelta Corsa HDs (nashbar special), and that rim is probably used on other Vuelta wheels, so I'm thinking it's not an unusual size. Might they be considered 15mm? Anyone know the official spec for those rims?
Nashbar's specs for the rim list the inner width as 16mm. http://www.nashbar.com/bikes/Product_10053_10052_566766_-1___ (click the "Specs" link)
This is a fairly standard width for road wheels, so you should be able to safely run any common road tire size (21mm-35mm give or take a few mm).