Originally Posted by
Bunyanderman
28's are "faster" and would match your weight better. If it fits your frame/fork.
The rolling resistence of some manufacturers 28 tires like Conti are less than 25 but not all. However the added aero drag of 28 more than offsets that. That's why the majority of pros run 23s and 25s with 25 common especially with the wider rims.