Have searched but couldn't find a definitive answer. Will the 2010 Roubaix (Comp) fit 28 tires?

I'm looking at similar models of both the Tarmac and Roubaix, both Comps with Rival. I know the Tarmac most likely won't fit the 28s, and the Roubaix would probably be slightly more suited to the newer relaxed position that I'm setting up.

Might want to specify whether Specialized or Fuji, both have a Roubaix. Assuming you mean the Specialized since you have the Tarmac mentioned.