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Basics of Tires, Inflation Pressure, Overinflate, Overloading Tires, Tire Essentials, tire pressure, tire safety, Travel Safety, Underinflate
It’s National Tire Safety Week, so this is a good time to discuss the topic of RV tires. Although I am a professional engineer, my area of expertise is not specifically in materials or road safety. I leave the topic of tire theory to Walter Cannon, executive director of the RV Safety Education Foundation (http://www.rvsafety.com). Walter has written many articles and produced many videos on RV tires and safety, and I highly recommend them to anybody who wishes to further educate themselves. This two-part article serves as a general overview of the basics of tires in order that RV owners may understand tire types, inflation pressure, and general use. In part one of this series, I will discuss the important topics of inflation pressure and loading.
Many RV drivers believe that it is appropriate to simply air the tires to the inflation pressure shown on the tire or vehicle ID plate. This is a dodgy oversimplification, as the listed pressure is the maximum design inflation pressure for the tire, and may not be a safe pressure for the RV load. The correct way to determine proper air pressure is to weigh the RV at each tire position and note the highest weight borne by each axle. Most tire manufacturers post recommended inflation pressures based on weight on their websites. Use your data to determine the correct inflation pressure for each axle as determined from the manufacturer tables.
Check the air pressure in each tire at least once a month, before each trip, and each morning before you drive. Tire pressure should be checked cold, as pressure ratings have been determined with typical running heat/pressure build-up in mind. Remember to check the air pressures of the inside tires on dual wheels and inflate all duallies on the same axle to the same pressure. Ensure the valves and caps are free of dirt and moisture.
Most people recognize the risks of overinflation, such as chance of blowout and poor tread wear. However, underinflation also carries significant hazards. Underinflation presents a higher chance of damage due to road hazards, reduces casing durability and fuel economy, and results in uneven or irregular tire wear. Additionally, Severe or prolonged underinflation brings about an increased risk of tread separation.
RV owners sometimes lower tire pressure in an attempt to create a smoother ride. This is not only dangerous, it’s relatively ineffective, as the difference in ride quality is not significant. When minimum recommended inflation pressures are not maintained, durability and optimum operating conditions for the tires are compromised. Therefore, tire inflation pressure should always meet at least the minimum guidelines for vehicle weight. It’s important to note that if the pressure in any tire drops by more than 20% of recommended inflation pressure, the tire should be professionally inspected before air is added. Personal injury may result from the tire separating from the rim while under pressure. A professional tire shop will use a cage to inflate the tire.
Overloading tires can have serious consequences for passengers and the RV. Too much weight causes stress on the suspension system, brake failure, shock absorber damage, handling and steering problems, irregular tire wear, and possible tire failure. Excessive load or underinflation can lead to an excessive amount of heat buildup, possibly resulting in tire failure. If you find that your tires cannot handle the load, lighten the load or install tires with a higher carrying capacity. Remember to consult your owner’s manual, tire retailer, or RV manufacturer for information concerning selection and installation of new tires.
In next week’s article, I will discuss RV tire types.
About the Author:
Steve Froese, an avid RV owner, traveler, and Coach-Net member since 2013, is the principal of “A Word to the Wise Technical Communications”, a published RV author, certified RV technician, and licensed Professional Engineer. He frequently collaborates with the “RV Doctor”, Gary Bunzer, and has worked with the RVIA/RVDA as a technical and training writer and consultant. Professionally, he works as a quality engineer and musician. Watch for more of Steve’s work in upcoming Coach-Net publications.
Karl P. UT~ “Kurt from Quality Tire was exceptional. He came and pulled both sets of back tires. The inside tires on both sides of our motor home had 0 pressure. Both Valve stems had been damaged for some reason. He replaced the valve stems on both tires, checked and filled all 6 tires to correct pressure. He was a pleasant and pleasurable person to work with. We were called by Coach-Net several times to make sure everything went as it was supposed to. Thank you to all the Coach-Net Representatives and to Kurt from Quality tire. It took something that was a pain and made it a pleasure.”
For many years I owned diesel pusher motorhomes before downsizing to a more modest Class C diesel. Aside from the larger amount of living space afforded by the pushers, another significant but often overlooked feature of these coaches are the hydraulic leveling systems. Although my late-model Navion has all the comforts of my previous motorhomes, I really miss the convenience and benefits provided by the levelers. Although many modern coaches of all sizes now offer hydraulic levelers available as standard or optional equipment, this is a relatively new offering on smaller units, and can be an expensive upgrade.
I recently had the opportunity to review a new product called the ReVo leveler. Although it does not provide actual leveling, for those without leveling systems in our coaches, this handy device is the next best thing. The ReVo leveler (
Both arrows will turn green when the coach is level. Although it is obvious when leveling front and rear which arrow indicates the front and which indicates the rear, it was less obvious when leveling left and right. The manufacturer could improve this by adding two more illuminated arrows pointing left and right. Despite this, the unit is easy to use, and it simply displays the number of inches that the vehicle is out of level. This can be directly translated to board or block height.
Navigating your RV through urban traffic is never fun, but toss in an RV trailer tire blowout at the same time and things can get life threatening if calm heads don’t prevail. The strength of your RV driving skills is measured by how you handle unpredictable situations like blowouts. Unfortunately the only way to determine where you stand is to actually experience one of these calamities, which is exactly what happened to us while maneuvering in a mess of interstate traffic.
“We have Coach-Net! That’s what it’s there for!” I pleaded. “You have good life insurance but I really don’t need a dead husband!” I added for extra drama. Maybe that’s what did it, but he relented and with a grumble said “Fine, call them.”
Waiting for it to be over was the hardest part, but we learned much from the experience. For starters, watching the repairman do his job made one thing obvious: he knew exactly how to park diagonally behind us so that if a car hit us all, his truck would take the impact first. Those RVers who try to do it themselves without a buffer of protection on the freeway practically guarantees a tragic outcome.
Ensure that the towing vehicle has the appropriate weight rating and power for the fifth-wheel trailer. Dealerships are obligated to ensure your towing vehicle is adequately rated, but it is always a good idea to do your homework.
When hitching a travel trailer, it is best to have a spotter assist with lining up the trailer hitch with the tow vehicle hitch ball. Make sure the trailer tongue is raised enough so the hitch just clears the hitch ball. Establish clear hand signals and/or voice commands with the spotter and have them guide the towing vehicle slowly and carefully to position the hitch ball under the trailer hitch. Lower the trailer fully onto the tow vehicle and lock the hitch onto the ball. Raise the trailer tongue again to ensure the hitch is properly locked onto the ball. Fully raise the tongue jack and connect the safety chains.
When you’re pulling your travel trailer behind you, it’s essential (depending on weight/length of your trailer) to use a weight distribution or equalizer hitch that will balance out your ride. Otherwise, too much weight in the front of the trailer will place excessive weight on the back of the towing vehicle, raising the front of your tow vehicle and causing loss of steering control, hitch dragging and braking difficulties. The key is to balance the weight over the axles and the hitch.
You can easily get your RV weighed for a fee at a truck stop; they’ll even give you a weight slip that shows the front axle and total weight. (For motorized RVs, it is recommended that the front axle account for approximately 33-35% of total weight.) Ultimately, you should take your RV to a professional weighing agency to make sure it isn’t overweight on the corners or axles.
