Originally Posted by thebulls

No worries, it is impossible to solve two equations for three unknowns!

I like Panaracer Pasela tires, 700x32, the non-Tourguard version because the lack of kevlar belts means that they have very low rolling resistance. On my single bike, they're definitely a faster tire than the Conti GP4 700x28's that I used to use.

For two otherwise-identical tires, a wider tire has less rolling resistance at a given pressure than a narrow one, because less deformation of the tire casing occurs as it is rolling. But of course, the narrower tire has to be pumped to a higher pressure to avoid pinch flats (thereby making the ride harsher). Higher pressure does not necessarily lower rolling resistance. Imagine riding on a solid steel "tire". Every tiny bump in the road forces the whole wheel (and bike and you) up and over the bump, absorbing energy in the process. Some of that energy is returned as you roll back down off the bump, but never quite all. By contrast, a tire just deforms around the bump, with measurably-lower energy loss (see articles in Bicycle Quarterly for details). The biggest factor determining how fast a tire rolls is how much energy is lost in the contact-area deformation. High-thread-count, low-resistance fabric (like cotton or silk) tires with thin rubber have the lowest rolling resistance (and lifetime). Thicker rubber &/or anti-flat belts increase rolling resistance. But of course, they may last longer and have fewer flats. But in 3000 miles of riding the tandem over the last year with Panaracer's we've had only one flat.