Thread: Tire Problem
View Single Post
Old 07-31-08, 06:43 AM
Senior Member
gregw's Avatar
Join Date: Sep 2003
Posts: 988
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
If that tire at 60 lbs looks half flat, then it's not a tire rated / designed for loaded touring. I would replace it. How much weight do you have up-front? Probably the front will be fine unless you have heavy front panniers as well.

On loaded touring bike, I like the rear tire in the high end of the recommended range and the front at the low end of the range. When un-loaded, they are both on the low end, nicer ride.

There have been several good articles written about tire pressure and rolling resistance, here is one from Sheldon Brown.

"Rolling Resistance
"Rolling resistance" is the mechanical friction generated as the tire rolls. As a segment of the tire tread rolls into contact with the road, it deforms from its normal curved shape into a flat shape against the road, then back to the curve as the tire rolls onward. The deformation of the rubber in this process is what causes the friction.
There are two ways to reduce this friction, each subject to trade-offs:

The thinner and softer the rubber/fabric of the tire are, the more flexible they become.
The trade-off with this is that the thinner the tire gets, the more fragile it is, and the sooner it will wear out.

The higher the air pressure, the less the tire will deflect.
The trade-off with this is that if you pump the tire up too hard, you lose the benefits of pneumatic tires: the ride becomes excessively harsh, and traction will be reduced. In addition, extremely high pressures require a stronger (heavier) fabric and stronger (heavier) rim flanges.

Rolling resistance does decrease theoretically with any increase in pressure, but with modern, high-quality tires the rolling resistance at correct inflation pressure is already so low that the infinitesimal reductions gained are more than outweighed by the trade-offs."
gregw is offline