The RV Safety & Education Foundation data indicates that 51% of RVs exceed one or more safety ratings. Exceeding Gross Vehicle Weight Rating and/or Gross Axle Weight Rating can lead to suspension failures, handling problems, difficulty stopping, and tire failures. A large number of RVs are traveling down the road on overloaded tires that could fail at any time, with potentially catastrophic results. There are many safety measures that need to be taken by RV owners to avoid fatal accidents.
Tires, like most manufactured products, are designed to operate within a specific load; we call this tire load rating. Each rating is accompanied by an inflation pressure that will give you the stated rating. This does not mean that this inflation pressure is correct for your motorhome. If you wish to achieve optimum life and performance from your tires, inflation pressure must be set based on the load being carried by the tire,
Every tire manufacturer publishes load/inflation tables for their products, which provides us with this critical information. Also, remember that the specified pressures are cold pressures; in other words, pressure in the tires before the tires start rolling down the road and heat becomes involved.
The fact is that motorhomes are not built symmetrically. The RV should be loaded equally on both sides. Motorhomes are equipped with slide-outs, generators, refrigerators, holding tanks, fuel and water tanks, and much more. The only way to properly weigh a motorhome to ensure that you are within your tire ratings is to weigh it by individual wheel position. Once you have done this, you can refer to the load/inflation table to determine the correct inflation pressure for your tires.
If the load on a tire is greater than the maximum rating shown on the sidewall, you must correct the situation. This can be done by reducing the load on the tire, either by unloading or redistributing the equipment in the coach or by upgrading to tires with a higher load capacity.
Expect to find a different load on each side of the axle. It’s important that all tires on the same axle be inflated to the same pressure, based on the heavier side. If doing so results in an overinflated tire on the light side, correct the situation by balancing your coach. An overinflated tire has reduced “tire patch,” or contact with the road, and may result in unsatisfactory braking, particularly on a wet road.
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.
Overloaded RV, with underinflated tires, can be catastrophic. In such a case, 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.
When parking your RV for extended periods of time, it is important to make sure the vehicle is as level as possible — to avoid tire overload due to weight transfers apart from convenience and comfort. On RVs without built-in leveling devices, 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 get damaged, leading to premature sidewall fatigue and ultimate tire failure.