Tire industry experts seem to agree that the two greatest contributors to tire failure are underinflation and/or overloading the tires. These two conditions cause heat damage which leads to tire failure.

Another condition that leads to tire failure is old age. The average life expectancy of an RV tire is not much longer than five years. The tread might look great, but tires just naturally deteriorate over time. In fact, the less they are used, the faster they deteriorate. A prudent person will replace their RV’s tires by the time they reach 5 years of age.

Safety-conscious RV owners will want to know the age of their tires, how much weight each tire is carrying, and how much air pressure the tire needs to support that weight.

To determine a tire's age look on its sidewall (usually the back side) for the letters DOT followed by one or more ovals containing numbers. The last oval will have three or four digits. If there are three digits, the first two are the week of the year and the last digit is the year of manufacture (the digits 229, for example, would indicate the tire was manufactured in the 22nd week of 1999). To distinguish between the 80 and 90 decades, tires manufactured in the 90's will have a triangular mark to the right of the manufacture date. Beginning with the year 2000 there are four digits. The first two are the week of the year and the last two are the year of manufacture (2301 indicates the tire was manufactured in the 23rd week of 2001).

Buyers of used RVs would be wise to check not only the physical condition of the tires, but also the date of manufacture molded into the sidewalls. They might want to adjust the purchase price to reflect the cost of a new set of tires.

And, just because the RV is new is no guarantee the tires are new. Tires may already be six months old when they are placed on the chassis by the chassis manufacturer. That chassis could sit in storage for months before the coach is mounted on the chassis. The finished RV may then sit on a dealer's lot for another six months before it is sold. If the tires are already two years old, you only have another three or four years before they will have to be replaced.

RV owners should weigh each wheel position of their RV and, using the tire-inflation tables supplied by the manufacturer of their tires, keep their tires properly inflated for the load they are carrying.

The load-carrying capacity and inflation pressure of a tire is molded into the sidewall of the tire.

It is important to note that the inflation pressure molded on the side wall of a passenger-car tire is the maximim air pressure for that tire. That is not the case, however for light-truck tires.

The inflation pressure molded into the sidewall of light-truck tire is the minimum (that's right, the minimum) air pressure required for that tire to carry the maximum weight molded into the sidewall of that tire. Using less air pressure means the light-truck tire must carry a lighter load.

While the tire-load rating molded into the sidewall of a light-truck tire should not be exceeded, it is generally recommended that the tire be inflated to the minimum pressure required to carry the load plus an additional 5 - 10 psi. The extra pressure will help the tire run cooler. It also acts as a reserve to offset normal loss of air pressure. But the extra pressure will not add to the tire's load carrying capability. Just keep in mind that the maximum air pressure for a light-truck tire is the minimum air pressure molded into the side of the tire plus 10 psi.

All tires on the same axle should be inflated to the same pressure. That would be the air pressure required by the tire carrying the greatest load.

If accurate individual tire loadings are not known, assume that the tires are loaded to their maximum weight rating and use the minimum recommended air pressure for that weight.

Check the tire pressure on that new RV... before you take delivery. Let's hope the RV manufacturer put the correct tire pressure in the tires before the RV left the factory. Otherwise, the RV may have been towed or driven from the factory to the dealer's lot, possibly to and from one or two RV shows, and then, in the case of a motorhome, taken on a number of test drives with inadequate air pressure in the tires. If so, those tires are candidates for premature failure.

Check the air pressure of your tires before taking the vehicle out of storage and placing it back in service. It is also recommended that tire pressure be checked every couple of weeks, and, ideally, each morning before traveling. Check the air pressure of the tires before they have been driven and while they are still cold. And use metal caps to seal the the valve stems and to keep them clean.

The Tire Industry Safety Council recommends that tires on vehicles with a GVWR less than 10,000 pounds be replaced when tread grooves are worn down to 2/32 of an inch depth. Place a penny upside down in the groove of the tire tread. If the tire does not reach Lincoln's forehead it is less than 2/32nds deep.

It is also recommended that tires on vehicles with a GVWR more than 10,000 pounds be replaced when tread grooves are worn down to 4/32 of an inch depth. Place a quarter upside down in the groove of the tire tread. If the tire does not reach Washington's forehead it is less than 4/32nds deep.

All-steel (as opposed to simply steel-belted) radial tires are recommended for vehicles with high gross-vehicle-weights such as motorhomes. The steel belt in the tire's side wall increases its durability as well as its resistance to sidewall damage.

We replaced the tires on our motorhome when they were five years old. They had been driven 85,000 miles. The tread still had a depth of about 5/32nds of an inch. We might have gotten another 5,000 miles out of them. But, since our next journey was going to be 10,000 miles of high-speed (60 - 65 mph) interstate driving, we decided to take the prudent approach.

Drive safe... don't run on tires that are old, overloaded or underinflated.