Proper Tire Inflation

The most important factors in tire care are maintaining proper inflation pressures, avoiding excess loading, inspecting tires regularly and driving with care at appropriate speeds.

It is important that your tires be properly inflated. Failure to maintain correct inflation pressures may result in fast and uneven treadwear, improper vehicle handling, and excessive heat buildup, which may result in tire failure.

To make sure you maintain the correct pressure in your tires, check the air pressure regularly with your own inflation gauge. Since RVs can be configured and loaded in many different ways, the proper inflation pressure should be determined by actual tire loads. The actual loads can be determined by physically weighing the vehicle. These loads will change from trip to trip, depending on how the vehicle is loaded.

Check your tires' air pressures at least once a month, before each trip, and each morning you drive during a trip. Inflation pressures should be checked when tires are "cold", that is, before they have been driven one mile. Heat generated during driving increases air pressure above the proper cold inflation pressure. This is normal, so never "bleed" air from a hot tire, since this could result in dangerous underinflation.

It may be difficult to check the air pressures of inside dual tires. However, it is important that these air pressures be maintained because the inside dual tires are subjected to high heat exposure (from brakes), lower air circulation and crowned road surfaces (which can cause inside dual tires to support more of the load than the outside dual tires).

Make sure all tire valves and extensions are equipped with valve caps to keep out dirt and moisture. Installing a new valve assembly is good practice whenever a tire is replaced.

The results of overloading can have serious consequences in terms of passenger safety. Too much weight for your vehicle's suspension system can cause spring, shock absorber or brake failure, handling or steering problems, irregular tire wear, tire failure or other damage. An overloaded vehicle is hard to drive and hard to stop. In cases of serious overloading, brakes can fail completely, particularly on steep hills. The load a tire will carry safely is a combination of the size of the tire, its load range and corresponding inflation pressure. Overloading your RV, with underinflated tires, can spell trouble.

Excessive loads and/or underinflation cause "tire overloading." As a result, abnormal tire flexing occurs, which can generate an excessive amount of heat within the tire. Excessive heat may exceed the tire's capabilities, which may lead to tire failure.

It is the air pressure which enables a tire to support the load, so proper inflation is critical. Since RVs can be configured and loaded in many different ways, air pressures must be determined from the actual loads (determined by weighing) and taken from the load and inflation tables provided by the tire manufacturer. These air pressures may differ from those found on the certification label. However, they should never exceed the tire limitation for load or air pressure.

If you discover that your tires cannot support the actual weights, lighten the load or install tires with a higher carrying capacity but do not allow the weight to exceed the GVWR of the vehicle(s).

Note: Installing tires with a higher carrying capacity only solves the problem of tire overload. It has no effect on the overloading of other components (i.e., rims, axles, shocks, or bearings). Rims may not be capable of withstanding the higher pressures necessary to support the load.

If the load cannot be adequately reduced, contact the RV manufacturer for advice.

If you decide to install a tire size other than that originally provided on the vehicle, care must be taken to ensure adequate load-carrying capacity and compatibility between the tire and rim.

If you have operated your vehicle with an underinflated tire, promptly have it removed from the wheel for a complete internal inspection to be sure it is not damaged. Tires driven even short distances while underinflated may be damaged beyond repair.

Tires should be inspected regularly for excessive or irregular treadwear, bulges, aging, fabric breaks, cuts or other damages. Remove any nails, stones, glass, etc., embedded in the tread to prevent damage. Even minor damage can lead to tire failure. Replace tires when the tread is worn to 2/32"** depth remaining in two or more adjacent grooves.

Built-in treadwear indicators, or "wear bars," which look like narrow strips of smooth rubber across the tread, will appear on the tire when that point of wear is reached. When you see these wear bars, the tire is worn out and it's time to replace it.

**On vehicles with GVWR in excess of 10,000 pounds, federal regulations require that tires on the front axle be removed when worn down to 4/32" depth. It may also be desirable to replace tires prior to wearing down to 4/32" to improve traction or vehicle handling.

Load and cold inflation pressure imposed on a rim/wheel must not exceed the rim/wheel manufacturer's recommendation, even though the tire may be marked for a higher load and inflation.

If your tires show uneven wear, ask a serviceperson to check for and correct any misalignment, imbalance, or other mechanical problem involved.

Tires will wear out faster when subjected to high speeds as well as hard cornering, rapid starts, sudden stops and frequent driving on surfaces which are in poor condition. Surfaces with holes and rocks or other objects can damage tires and cause wheel misalignment. When you drive on such surfaces, drive on them carefully and slowly. Before driving at normal or highway speeds, examine your tires for any damage, such as cuts or penetrations.

Check your tires frequently for scrapes, bulges, cuts, snags, or impact damage. Damage can occur to the inner portions of your tire without being visible on the outside. While driving, if you experience a sudden vibration or ride disturbance, or if you suspect that damage to your tires or vehicle has occurred, immediately reduce your speed or stop. Drive with caution or have your vehicle towed to the nearest vehicle or tire dealer to have your vehicle inspected.

When a tire is losing air it must be removed from the wheel by an expert for complete internal inspection to be sure it is not damaged. Tires driven even short distances while severely underinflated may be damaged beyond repair.

Punctures up to 1/4" in diameter, when confined to the tread, may be repaired by trained personnel. These tires must be removed from the wheel, inspected and repaired using industry-approved methods which call for an inside repair unit and a plug. Some punctures may make the tire non-repairable. A plug by itself is an unacceptable puncture repair.

The repair material used -- for example, a "combination patch and plug" repair -- must seal the inner liner and fill the injury to be considered a permanent repair. Never use a tube in a tubeless tire as a substitute for a proper repair.

Aerosol Inflators

Do not depend on tire aerosol sealants and inflators to permanently fix a damaged tire. These products are designed to provide only a temporary, emergency repair to help get you off the road and to the nearest tire repair facility. They may also make the tire non-repairable.

Some aerosol products of this type use flammable gases, such as butane, propane or isobutane as propellants. Follow all directions and precautions printed on the canister when using these products. Be sure to inform tire service personnel when you have used any flammable aerosol to inflate your tire.

The purpose of regularly rotating tires is to prolong their useful tire life by achieving more uniform wear for all tires on a vehicle. Before rotating tires, check your owner's manual for rotation recommendations for specific vehicles. If no rotation period is specified, rotate your tires every 6,000 to 8,000 miles or at any sign of uneven wear. If the tires show uneven wear, ask a serviceperson to check for and correct any misalignment, imbalance, or other mechanical problem before rotation.

Rotating the tires as recommended by the RV or tire manufacturer will help even out the amount of wear on each tire and extend the life of the entire set.

Note: Some kinds of tires cannot be rotated in the manners described below. Such tires include uni-directional tires and tires with asymmetric tread designs. Also, some vehicles may have different-sized tires mounted on the front and rear axles, and these different-sized tires have rotation restrictions. Check your owner's manual, or with your tire dealer, for the proper rotation recommendations for these special cases.

When tires are rotated, the inflation pressures must be adjusted for the tire's new positions in accordance with the actual loads on that wheel position. Underinflated or overinflated tires may result in poor handling, uneven treadwear and increased fuel consumption.

Note: Lugnuts should be properly torqued anytime a tire/wheel/rim assembly is re-installed on the vehicle.

When parking your RV for extended periods of time, it is important to make sure the vehicle is as level as possible -- not only for convenience and comfort purposes, but also to avoid tire overload due to weight transfers. On RVs without built-in leveling devices, it is customary to "block" the low wheel positions.

Extreme caution must be taken to ensure that the tires are fully supported when using blocks. The load on the tire must be evenly distributed on the block and, in the case of duals, evenly distributed on blocks for both tires. If this isn't done properly, tires can be damaged, leading to premature sidewall fatigue and ultimate tire failure.

The illustrations below show the correct and incorrect blocking methods.

Tire Blocking