Goodness, Continental Grand Prix 4000s II 28mm tires run large

I have Fulcrum Racing Quattro LG wheels with an internal width of 17mm.

I have Conti GP 4000s II tires in a 28mm size mounted on my Synapse.

While the tires do work great, I think I would be generous to say there's 2mm clearance on either side of the rear wheel at the chainstays. More like...