Tires used on most RVs are driven at or near maximum loads during hot weather and then are left idle for months. In normal use oils in the tire come to the surface during flexing and protect the rubber from ultraviolet light. But when left idle natural aging may cause the rubber to crack prematurely, especially in the sidewall area.

Any tire on an RV that is over five years old should be inspected by a competent tire professional for cracking and replaced, even if it has no apparent tread wear. This is because a tire on a car or truck might last 80,000 to 120,000 miles before it needs to be replaced, but an RV tire that only travels 5,000 miles per year will not approach that mileage for 20 years. It will need to be replaced much before that.

The first step is choosing a tire adequate for the load. The load rating printed on the sidewall will show the maximum load that can be carried at a defined pressure. As the inflation pressure drops, the load that can be carried is less. As speed increases, the amount of load that can be carried also drops. The load rating is also affected by how the tire is used, as a single or as a dual.

A pair of Michelin XRV 225/70R19.5 tires inflated to 75 psi will allow the front axle of a motorhome to carry 6,080 pounds, or 11,440 pounds as a pair of duals on each side of the rear axle when driven at speeds up to 75 mph. If the inflation pressure was only 55 psi, the load carrying ability is reduced to 4,950 pounds on the front axle and 9,290 pounds on the rear axle. This would be the easy way to overload the tires, cause fast tire wear and possibly result in a blowout. During a hard braking manoeuvre, weight from the rear of the vehicle is transferred to the front tires. If there was not enough safety margin, the front tires could easily be overloaded by this transfer of weight.

Diameter, profile, inflation pressure, sidewall strength and speed rate tires. An ST225/75R15 tire is a special trailer tire with a section width of 225 mm, a height to width ratio of 75%, radial construction with a diameter of 15 inches. As the width to height ratio becomes smaller, the tire has a lower profile. LT stands for Light Truck and P for Passenger service. (Top)

The DOT number on the sidewall identifies the manufacturer, plant where the tire was built, the type of construction, and the date of manufacture. The date 423< is defined as built in the 42nd week of 1993. The triangle symbol denotes the 90s decade. Tread wear is given as a number, 100, 120, or 130. The higher the number, the more resistant the tire is to wear.

Like the rest of your RV, the tires need to be cleaned. Always use a soft brush with a mild soap. Don’t forget to clean the surfaces between the duals, the backside and be sure to rinse off the soap. Tire dressings that use any petroleum products or alcohol can cause premature ageing of the tire by reacting with the antioxidant compound in the tire. Since RV tires are used over a longer time than passenger car tires the chemicals have a much longer period to eat away at the surface.

Before putting your RV away in storage for the winter, clean and rinse the tires, cover them to protect them from ultraviolet rays and check the tire pressure. Tire pressures should be checked when they are cold or have not been driven more than a few miles. Use a truck style pressure gauge and install extensions on the valves so that you can check the pressure without having to take off the hubcaps. It is difficult to see an under inflated inside dual tire, so checking the pressure is the only way to go.

If you pick up a nail, do not have it fixed by installing a plug from the outside. Have the tire dismounted and a repair made from the inside. This is the only way to properly inspect for damage to the inside sidewall. Do not depend on aerosol sealants and inflators. These products are designed to provide a temporary, emergency repair to help get you to the nearest tire repair facility. Be sure to tell the tire service personnel when you have used any aerosol inflator as a temporary repair, as many of them use a flammable gas as a propellant.

When you are replacing the tires on your RV, buy the same quality tire or one of greater load strength. If you buy a new larger tire check to see that it will carry the weight, not exceed the rim capacity, give adequate clearance in the wheel wells, and between the duals. Duals that rub against each other as they flex will heat up and cause either one or both of the tires to fail.

Tires must transmit driving, braking and cornering forces to the road in good weather, rain or snow and should resist wear and punctures. Tires that are properly inflated, not overloaded, kept in proper alignment will give you a smooth cushioned ride, good traction and many worry-free trips.(Top)