Originally Posted by
bradtx
Measure the width inside the chainstays, the clearance between the top of your 25 mm tire to the brake bridge and the same for the fork.
Brad
+1 Measure the clearances all around and see how much room you have. I'd be very surprised if you can even go to 700x28 considering you have a sports road bike and they aren't usually designed for big tires. If you plan to commute year round, a casual (not serious racing) cyclocross frame would be much more versatile as they will usually take wide tires and even wide tires with fenders.