RV Tire Safety
with RV tire expert Roger Marble
One of the forums I follow is on Airstream trailers. There was a post from an owner who was having problems getting the actual loads on the trailer, hitch and tow vehicle. There were a number of posts on what he needed to do; however, I saw no mention of tire loading or tire inflation so I added the following post to the thread:
When you are done making adjustments and moving stuff around and get new scale readings, you need to look at tire loading and inflation. Ideally, you would get the individual axle load as they are probably not split 50/50.
You are also probably not 50/50 side-to-side loaded either. The good news is that you don’t have slides or a residential refrigerator so are probably 51/49% side-to-side or 48/52%.
The best approach is to take the heavier loaded axle and assume a 52/48% split and compare the 52% number with the tire load capacity. You should have at least a 15% load capacity margin, i.e., 52% of the heavier axle is no greater than 85% of tire max capacity.
Finally, with a multi-axle trailer, you should use the tire sidewall pressure number as your “Cold Tire Inflation” to try and lower the Interply Shear forces that are trying to tear the tire belts off the carcass.
NOTE: While I wrote this in response to a specific post/question on an Airstream forum, the information on tire load and inflation would apply to similar trailers that do not have slide-outs or heavy residential refrigerators or other obvious unbalanced equipment.
Read more from Roger Marble on his blog at RVtiresafety.net.