[arcosine]

Its a law of physics, not a dumb table.

The contact pressure equals the inflation pressure of the tire, period. The load equals the pressure times the contact area.

A narrow tire will had a narrow contact patch, a wide tire will have a wide contact patch. At the same inflation pressure, the narrow tire's belt will deflect more. The energy lost to deflection of the tire is 1/2 times the loss stiffness times the deflection squared. The imaginary stiffness, the part that absorbs energy is related to Tan delta (loss modulus) for the rubber compound and the construction of the belt. Silica reinforced compounds and compounds with tighter cures have lower tan delta that carbon black reinforced NR/BR compounds.

Lets take 2 cases; a 1 inch wide tire and a 2 inch wide tire, same pressure, load,construction and diameter.

The one inch tire deflects twice as much, but the belt is half a stiff, so it has twice the rolling resistance. But the 1 inch tire can be inflated to twice the pressure without over stressing the cords, so now the deflection is the same as the 2 inch tire, but has half the rolling resistance.

Tony Levand