Dan, I'm not certain how much clearance you have on the Strada frame, but I believe it's more than on my Corsa, so you could probably run a 571x28 on the rear, but I'm not so sure it would clear on the front. The brake boss is the biggest clearance problem on the rear of a Corsa, and some people grind on it for more clearance, but I really don't know for sure about a Strada. As I recall, though, 571x28's are rare, and the few made aren't really that wide (it's amazing how many tires don't really measure what they say).
 
Even on my Corsa, with 559's, there is plenty of room for tires wider even than the 28's I ran for a while. I don't know exactly how much wider, and like I said, the Strada probably isn't exactly the same as a Corsa.
 
I really liked the 559x28 Conti Grand Prix's that I ran. I don't think they're making the new GP's in a 559x28, but there are plenty of old stock ones still around. They were very impressive on chipseal.