Is there an age limit on tires? What you should know for RV tire safety

I think a good response to the question “Is there an age limit on tires?” would be: Tires are like people. They can look great on the outside but be a mess on the inside.

The physical appearance on the outside can tell you there is a problem. Those might include sidewall cracking, or a bulge from an impact, or irregular wear which can indicate possible tread detachment or maybe an alignment issue. However, you cannot tell what the inside of the tire looks like—and that’s what’s important. Michelin recommends a professional inspection of tires at five years old and every year thereafter.

Professional inspection of tires?

What is a professional inspection? One where each tire is removed from the RV, removed from the wheel (rim), and inspected inside and out, and then remounted.

A professional inspection is NOT having someone from the local tire shop look at the tires from the outside and asking how they hold air pressure.

Tires older than four or five years have an increased susceptibility to having bead damage when removed. Even if you do not sustain bead damage, it’s going to cost you $100 to $300 to have each tire inspected, each year.

This is recent post from a motorhome owner:

“We changed out our 6 Michelins last fall for Toyo M154. The Michelins had less than 20,000 and looked brand-new; they were 7 years old. Four of six tires had broken cords showing through on the interior of the tire. That was enough for me to realize you cannot go by the tire’s mileage, if it holds air (they did), or how they look. The insides are breaking down….”

Some causes of potential damage to tires

• Tires have UV-protecting chemicals inside, but the tires need to be spinning to keep the chemicals dispersed. There also are other chemicals that help longevity that also need to stay dispersed in the tire. Tires that sit in one place a lot, like RV tires, have a lower life than ones that are spinning on the road for many thousands of miles each year because the flexing disperses the chemicals in the tire.
• Ozone and UV can damage tires very quickly. It does not matter if an RV is stored inside and climate-controlled, if someone uses an arc welder or has electric motors in that garage without good ventilation.
• Bad roads cause a real hit to tires, for real. Potholes and rough roads can break the cords inside the tire, yet the breaks may not be seen from the outside. I have previously posted on the 100% correlation with tire failures and hitting large potholes.
• Underinflation is the killer of tires, yet we constantly read posts from people saying to lower the tire pressure to improve the ride.

Use a tire pressure monitoring system (TPMS)

Should an RV owner be using a TPMS to help detect low tire pressure tires? Absolutely.

• Unlike car tires that typically have a 20% to 30% or more safety margin, RV tires are only required to have a 10% safety margin, and only if the RV was built after August 2018.
• RVs built before September 1, 2018, are required to have precisely zero safety margin. In other words, those RV tires can barely support the axle design weight, so you’re running them at close to 100% all the time. Studies show that the MAJORITY of RVs have one or more tires in overload.

What is the “safety margin”?

So what does “safety margin” mean? That’s the difference between how much weight an axle is designed to support and how much weight the tires on that axle are designed to support when the tires are inflated to the pressure found on the Certification Label or molded into the tire sidewall (when the tires are cold). The closer you run anything to its maximum design rating, the more likely it is to fail prematurely.

Remember, the pressure in the tire manufacturer’s load inflation chart assumes that the left–right weight distribution on the axle is perfect (no difference from one side to the other). Yet it’s not uncommon for RVs to have up to a 10% weight imbalance from one side to the other.

Weight distribution on an axle

Many larger RVs are found with 1,000 to 1,500 more load on one end of an axle than the other. When you do a CAT Scale weighing, you are seeing the average weight, not the per-tire weight. That means one side of an axle has a tire that likely is underinflated for the actual weight, IF you just inflate the tires to the pressure in the load inflation chart. Why? The pressure in the load inflation chart is the MINIMUM pressure needed to support that weight, not a “recommended” or “optimum” pressure. It’s the bare minimum.

In closing, we’re all used to replacing tires on a car when the tread wears down. For most of us I’d wager that’s about every five years or sooner, if we’re still driving to and from work. That means most of us have no idea of the impact of tires aging out because we replace our car and truck tires before age becomes a factor.

Trying to match our car tire experience with an RV experience may turn out… poorly.

For what it’s worth.

Roger Marble

Check out my Blog www.RVTireSafety.Net

Read more from Roger Marble on RVtravel.com.

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