Originally Posted by Gtscottie
My wife and I are planning a loaded tour this July we are planning to carry rear panniers and pull a BOB trailer. Combined team weight is 330lbs. We have 700x26c Specialized turbo sport tires on our Santana Arriva. I am wondering if these are adequate or if we should go to wider tires?
Strongly consider at least a true 32mm rear tire if your rim is wide enough (which I suspect it is - See:
http://www.sheldonbrown.com/tire-sizing.html#width). For Avocet tires, run one size larger as their tires all run small, e.g., a 28mm is about 26mm; 32mm is about 29mm. Front could either be the same as rear or 28mm; all depends on how many spares you want to carry as you'll want to have at least one larger size available for the rear. LBS shops always have skinny tires on hand that can be used for the front.
Rationale: While more narrow tires are sometimes preferred for sport riding, a wider tire is the logical choice for all other types of riding and, in particular, touring. While a properly inflated, wide diameter tire will not "feel" as crisp through the corners as a narrow, high-pressure racing tire, it actually has more traction, it really doesn't suffer from an increased rolling resistance, it will out last the more narrow tire by a significant margin, and will be far more comfortable for both riders than a more more narrow tire that would have to be over-inflated to achieve the right "shape" for practical use while touring.
Some additional reading on tires:
Generally useful, tandem-specific advise from Mark Johnson:
http://www.precisiontandems.com/arttiresbymark.htm
General info on tires:
http://www.sheldonbrown.com/tires.html