Towable RV Tire Requirements
By Mark S. Nemeth  #45776

This article originally ran in the March/April 2002 issue of
Escapees magazine
Reprinted by permission

Towable RVs have some special tire requirements. With today's large trailers and fifth wheels, it is possible to have a catastrophic tire failure on your rig and not even be aware of it. Often, this will allow you to travel along until passing motorists tell you by waving frantically that you have a problem "back there". When a tire self-destructs, it often does significant damage to the rig and may also result in loss of control. The best way to avoid all this is to use the correct type of tire for your unit and take good care of them.

Unless specifically instructed otherwise by the trailer manufacturer, you should use only tires that carry the "ST" designation on your trailer or fifth wheel. The ST stands for Special Trailer and tires with this designation are designed differently from the average car or truck tire. They incorporate different tread designs and many have additional belts in the tread and sidewalls. The rubber compounds used in the tires are UV stabilized to help reduce damage caused by exposure to the sun. ST tires also come in higher load ranges to accommodate the weight of larger RVs. Be sure to pay attention to the weight rating of the tires you select for your rig. Don't just assume that the tires that are on it right now are the correct ones, check the owner's manual or contact the RV manufacturer for the correct type and load rating for your application. An overloaded tire will fail, often spectacularly, and we don't want that!

Inflation pressure is critical to the life of your tires and to your safety. Get a load chart from the tire manufacturer and weigh your rig. Divide the weight of your rig on the axles by the number of wheels to get the weight carried by each tire. When the tires are cold, inflate the tire to the required pressure and check it often. Always check your tires when they are cold… never after you have been driving and never let air out of a hot tire! Under-inflation kills more tires than road hazards. If you want the ultimate in peace of mind, you might consider purchasing one of the wireless tire pressure monitors available through RV dealers and camping catalogs. These units mount on each wheel to continuously monitor the pressure and send a signal to a remote readout on the dash. An alarm sounds if any tire drops below a preset pressure. If you prefer not to invest in one of these gadgets, simply add a small mirror or two to your existing tow mirrors that allow you to see the tires on both sides of your rig. A glance in the mirrors every few minutes will help you catch tire problems before they go critical.

Alignment affects tread life. Many trailers have alignment problems due to bent axles or manufacturing problems and it's not uncommon to have one tire that wears a lot faster than the others. An alignment shop that works with RVs can correct many of these problems. A quick check is to measure the distance between the centers of each wheel hub on both sides of the RV. They should be the same, or shouldn't vary by much more than 1/8". If the distances are significantly different, then you should consider corrective work to keep your tires from wearing poorly.

Severe impacts can damage any tire and lead to early failure. Tires that show no obvious signs of impact damage can fail suddenly on down the road. With a trailer or 5ver, it's important to avoid hitting a curb or driveway edge during a turn. If you must go over one, do it as slowly as you can to minimize stress on the tires. If you hit a severe pothole or nail the edge of a curb really hard, it's a good idea to get the tires (and also the suspension) inspected for signs of damage.

Improper use of leveling blocks can ruin your radial tires! Always make sure that the entire footprint of each tire is fully supported when using these devices. Never attempt to use bricks, rocks or 2x4s and avoid sharp edges that can cut the tread.

Tires are a big investment and are critical to your safety and the safety of your rolling home. It's worth a little extra effort to care for them properly. Get in the habit of visually inspecting all the rubber on your rig each time you prepare to break camp. Look for signs of impact or puncture damage or any indication of unusual wear or under inflation. Check the sidewalls for wavy spots or bulges that could warn of tread or sidewall separation. Check the tire pressures as often as possible, or at least every couple of weeks when you are traveling. Never overload a tire. And the best advice of all: Slow Down! Slower speeds reduce tire heating and wear and will also give you time to appreciate the scenery as you drive along. Happy Trails to you and don't forget to keep the rubber side down and the shiny side up!

This page last updated on September 8, 2002