RV Tires 101 People tend to remember large purchases. Things such as your home or your coach are hard to forget, however, some smaller purchases stay with us, the dates sometimes get blurry. An example is tires. Buying tires for your coach is not a small purchase and most people remember the last time they did so. Sometimes it seems that we just bought tires, when in fact it was six or seven years ago. When should you replace the tires on your RV?
Before we answer this question, let’s consider how tires are built and how they wear. Tires are composed of various types of material and rubber compounds, having performance properties essential to the proper functioning of the tire itself. These component properties evolve over time. For each tire, this evolution depends upon many factors such as weather, storage conditions, and conditions of use (load, speed, inflation pressure, maintenance, etc.) to which the tire is subjected throughout its life.
Let’s consider each of these factors starting with weather. Temperature extremes have a negative effect on tires. If your coach spends time in an extreme atmosphere this will contribute to the lessen of its lifespan. When the temperatures change you may notice a change in the pressures in your tires. This applies to tires in your coach and in your other vehicles as well. As temperatures begin to rise the air in the tires to take up more volume and thus increase. The pressures also increase as you drive the vehicle, and the tires heat up from the rolling friction. Tires generally experience an increase in pressure of 1 psi during each 5-minute interval of driving in the first 15 to 20 minutes of driving. Afterthat the pressures stabilize.
Cold temperatures cause the air in the tire to take up less volume and thus the pressures may drop. Pressures can drop 1 to 2 psi for every 10o drop in temperature.
Checking tire pressures before each trip is an important part of maintenance. If you do not have the capacity to add air to your tires at home, you will probably have to drive to a facility with air available. Before you leave to travel to that facility check the pressures in each tire and record them. When you arrive at the facility measure the pressures again and add the amount of air needed to reach the recommended cold pressures from your notes (when you checked the tires at home). If your tires were at 90 psi at home (cool), the recommended psi is 100 psi and when you arrive at the facility to add air the reading is 95 psi you will need to add 10 psi to reach the recommended cold psi. The pressures listed on the sidewall of the tire are maximum for the maximum load for each tire. The correct pressures for your vehicle are usually listed on a decal located near the driver’s seat. It can be on the driver’s door (if equipped) or on the side wall next to the driver’s seat.
Tires will lose air over time as air migrates thru the tire. Nitrogen has proven to move thru the tire slower since it has a larger molecular structure. Nitrogen is more expensive and can be more difficult to find.
Underinflated tires can cause a loss of steering control, tire deformation during cornering, buildup of excessive heat, faster tread wear, decreased fuel efficiency. Overinflated tires can cause a harsher ride, susceptible to blowout and damage from potholes and debris as well as increased stopping distances. So, we can see that proper tire inflation is important for vehicle safety and increasing the useful lifespan of the tire. Even if you have a Tire Pressure Monitoring System (TPMS) on your vehicle, it is still a good idea to check the tire pressures before each trip as part of your pre-trip check.
Tires are not designed or built to last forever or even the life of the vehicle.
This service-related evolution varies widely so that accurately predicting the serviceable life of any specific tire in advance is not possible.
Next time we will look at other aspects of tire safety.
Stay Safe and get On The Road.
Butch Jones, Safety Chairman
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