As tire pressures have become as controversial as gun control, global warming and paper vs plastic, I hesitate to get into these discussions. I am not a tire expert. My “experts” are Michelin and Goodyear Field Service Manager-- RV specialists, & RVSEF (Recreation Vehicle Safety Education Foundation). They all work with RV tires and tire safety on a daily basis, unlike the local tire store. We are all adults here.... you believe who you want to believe.
At the big rallies (FMCA, Good Sam, Escapades, etc) there is usually a tire manufacturer rep, an RV specialist, who will give you a good education on how RV tires are made, the specs and the special circumstances that come into play for this segment of the tire industry. For those that don't “do” rallies, if you ever find yourself near one, do your best to sneak into a tire rep's seminar.
Those of you worried about over inflating a tire: yes it is possible, but blow outs from over inflation are rare. The tire is designed to have a cold max pressure and a 'working' pressure. The air pressure is supposed to increase as it rolls along the highway. The usual consequence of over inflating a tire, *not* beyond its cold max pressure, is uneven wear of the tire tread, but that only comes into play if the tire is more than 15 psi over the recommended load rated pressure.
Michelin, Goodyear and RVSEF all recommend trailer tires should be inflated to the max cold side wall pressure, as long as the rim is also rated to that max pressure. Under inflated pressures allow the side wall flexing that generates heat, a known killer of tires. Some people lower their tire pressures for the comfort of their fine china & other delicates they have packed in their trailer. You may want to rethink the loading & packing of your trailer. A blown tire causing thousands of dollars in damage, not to mention the danger of being injured or killed while disabled on the side of the highway, out weighs the softness of the trailer ride. At least in my book. Over 700 people are killed annually due to accidents while their vehicle is broken down on the side of the road.
If you know for sure the weights being carried by each tire, do the math and figure how close to the rated tire capacity your tires are. A G rated tire that has a max load of 3750lbs at 110 psi will be running at 95% of its max capacity carrying a load of 3550lbs. That means that tire is running close to its max, 100% of the time, sitting or rolling. It has been my experience that anything working at, or close to 100%, is subject to early failures. All tires on the same axle need to be inflated to the same psi.
You can find Goodyear RV tire inflation charts at
www.goodyear.com.
You can find the weights of 49 Mobile Suites at the Yahoo site
http://autos.groups.yahoo.com/group/mobilesuites/ under Files.
You can find “Guaranteed Tire Failure” by John Anderson, founder of A Weigh We Go, now the RVSEF, at
http://www.rv-news.com/mar2000/feature2.htm
I have the most frequently weighed 5th wheel trailer in history & my tires are always at 110 psi. If I had the 17.5 in tires, they would be inflated at 125 psi. You make your choices & you choose your consequences.
Despite doing everything according to the "experts", tires still fail. I don't want to see anyone on the side of the road with a tire issue & wish everyone safe travels.