Originally Posted by
Myosmith
Does anyone know of any data showing just how much tire width affects rolling resistance. For example using the same wheel and the same make and model of tire, how much does rolling resistance increase going from 23mm > 25mm > 28mm > 32mm? I've been told that within this range wider tires actually have lower rolling resistance but that above certain speeds the increased aerodynamic drag cancels the benefit. This is counterintuitive but would be of benefit to a clyde like me.
Is this accurate and does anyone have data one way or the other?
Also, doesn't the increased weight of the wider tire decrease performance?
Thanks
Assuming that two tires are made out of the same materials
and are at the same pressure, the wider tire will have less rolling resistance because the wider tire will have less deformity to get the same size contact patch as the thinner tire.
If wider tires have less pressure, then it is no longer obvious what happens. Assuming the tires have the same pressure, you are right, the wider tire will have more aerodynamic drag. Since aero drag is proportional to the square of speed and rolling resistance is proportional to speed, there is a speed at which the two tires should have the same total resistance. That speed depends tires, pressure, total weight, phase of the moon (o.k., not the last one)...
Cheers,
Charles