Originally Posted by
jsdavis
Don't be too tempted to go narrower. A narrower tire doesn't necessarily have less rolling resistance and may in fact have more because the tire deforms more and becomes less round than a wider tire. This is assuming you are comparing similar tires. Assuming the same pressure, the wider tire deforms more in the width and less in the circumference so it stays more round than a narrower tire..
except narrower tires inherently use higher pressures. a 25c tire probably has 110-120psi in it, while a 35c hybrid tire is more like 60-80psi. if the same weight rider put 60psi in that 25c, they'd pinch flat the first time they hit a crack in the pavement.