Originally Posted by Don in Austin

The slower you are going and the harder the climb, the less difference the tires make. When you are struggling up a steep hill the overwhelming % of the work you are doing is propelling the weight of bicycle + rider to a greater elevation -- rolling resistance of the tires is almost completely immaterial. The only difference the tires will make is how much of a run you can get going downhill to carry you partly up the next hill. You have to be moving quite fast before aerodynamics of the tires are any more than a theoretical consideration, rolling resistance is more important.

Don in Austin