Originally Posted by
Homeyba
I don't about that chart Ritterview. My team is in the 350 range and run 23's and 25's at 120psi. According to that chart we should be inflating our tires to something like 160psi for the 25's and 200psi for the 23's (if I'm reading that chart correctly). None of my tires are even rated for those pressures.
The chart is attempts to give the pressures at which the tire deflection is held constant. It is not a chart for safety but rather the author's feeling of the pressures yielding the lowest rolling resistance. I feel that chart is a good starting point but as Homeyba points out there is much room for teams to go outside its recommendations depending on what your team likes and the road surfaces encountered.
I think most people would agree that when holding the pressure constant a heavier team will deform the tire more than a lighter team. Likewise that more tire deformation can increase rolling resistance. As a result I believe the chart does a good job pointing out that if 23mm tires are at 120 psi is the fastest setup for a 200 lb load then it may not be for a 350lb load.
Personally I like wider tires so that I can ride faster and more aggressively over cracked rough roads, railroad tracks, and cattle grates.
Below is a link to a good discussion of the chart, tire choice and inflation at Precision Tandems.
http://www.precisiontandems.com/arttiresbymark.htm