What about tire size and the rule of 105?

The rule of 105 is based on the aerodynamic efficiency of tire size.  The rule of 105 does not take into account the speed gains from a wider tire at lower tire pressures.  To explain further, the aerodynamic cost of a wider tire (say 25c to 28c) is lower than the savings you see in rolling resistance, so if you want to be faster, ride a 28c tire.