Wiggle's Cock Up=your Saving..

BringMeMyFix
But just rolling along, there's less rolling resistance, due to the way the tyre deforms, physics of contact patch - wider tyre has shorter/wider contact patch, and it's the length of patch that effects rolling resistance.

I'm not so sure about that, the deformation of the tyre would depend allot on the amount of weight on the bike, and:

"Standard friction equation

The standard equation for determining the resistive force of friction when trying to slide two solid objects together states that the force of friction equals the coefficient friction times the normal force pushing the two objects together. This equation is written as

Fr = ?N

where:

* Fr is the resistive force of friction
* ? is the coefficient of friction for the two surfaces (Greek letter "mu")
* N is the normal or perpendicular force pushing the two objects together
* ?N is ? times N

Fr and N are measured in units of force, which are pounds or newtons. ? is a number between 0 (zero) and ? (infinity).
Applies to static and kinetic

This equation applies to both static and kinetic sliding friction. Static friction is the friction before an object starts to slide. Kinetic friction is the friction when the object is actually moving or sliding.

Static friction and kinetic friction have different coefficient of friction values.
Independent of area for sliding hard surfaces

An interesting result of this equation is that in the case of sliding friction of hard surfaces, the friction is independent of the area of the surfaces. In other words, it is just as difficult to move a 1 square-cm object as a 1 square-meter object, if they both are pressed to the surface with the same amount of force.

This is not intuitive. You would think that there is more friction when the surfaces are larger, but the friction equation states otherwise. You can verify this fact with experiments.
Soft, adhesion, rolling and fluid

In situations where the surfaces deform or there is molecular adhesion, the friction is not independent of the areas in contact. In these cases surface area usually comes into play. This is also true for rolling and fluid friction.

When solid surfaces are soft and deform or when one material is a fluid, the shape of the solid object may be a factor.

Although the standard friction equation still holds, the coefficient of friction may have area, shape and other factors included in it....

...Coefficient when surfaces not hard and sliding

In the case where a surface is soft, there is molecular adhesion, and in rolling and fluid friction, the coefficient of friction is not a simple number. The coefficient may be dependent on the area of the surfaces, the amount of deformation, the amount of adhesion, the shape of the surfaces, the radius of the wheel or the viscosity of the fluid.

What this means is that although the standard friction equation holds in these cases, the coefficient of friction will only hold for a specific configuration. In other words, you can't accurately give something like the coefficient of rolling friction for a rubber tire on pavement without stating the type of rubber, area on the pavement, inflation of the tire, and its tread pattern."

sorce