My canned response on RV tire ages:
Tires are like people. They can look great on the outside and be a mess on the inside.
While the physical appearance on the outside can tell you there is a problem, such as sidewall cracking, you cannot tell what the inside of the tire looks like and that's what's important. Michelin recommends a professional inspection at 5 years old and every year thereafter.
What is a professional inspection? One where each tire is removed from the RV, removed from the wheel (rim), and inspected in 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.
But tires older than four 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 up to $300 to have every tire inspected, each year.
This is a very recent post from a motorhome owner:
"We changed out our 6 Michelin XRV's last fall for Toyo M154. The Michelins had less than 20,000 and looked brand new, they were 7 years old. 4 of 6 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...."
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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, potentially have a lower life than ones that are spinning on the road for many thousands of miles each year because the spinning disperses the chemicals in the tire. Of course, the ones spinning for many thousands of miles each year usually wear the tread out first.
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Ozone can damage tires very fast. It does not matter if an RV is stored inside and climate-controlled if someone uses an arc welder in that garage without good ventilation. The same happens with large electric motors in the garage that have brushes. The sparking can generate ozone.
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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.
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Underinflation is the killer of tires yet we constantly read posts from people saying to lower the tire pressure to improve the ride.
On a related topic, should an RV owner be using a TPMS (tire pressure monitoring system) to help detect low tires, especially while driving or towing? Yes.
Unlike car tires that typically have a 20% or more safety margin, a towable RV's tires are only required to have a 10% safety margin, and only if the RV was built after August 2017 (per RVIA towable standards). Towable RV's built before Sept. 1, 2017 were required to have precisely zero safety margin by the RVIA. In other words, those towable RV's may have tires may barely support the axle design maximum weight so you're likely running them at close to 100% all the time, or maybe even overloaded.
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 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.
The Federal Motor Vehicle Standard (FMVSS) 120 covers tire and rim selection for vehicles in excess of 10,000 lbs GVWR. FMVSS 110 covers vehicles of 10,000 lbs GVWR and under.
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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 RV's to have up to a 10% weight imbalance from one side to the other. Even worse, a friend with a well-known brand fifth wheel of recent vintage has a whopping 22% difference between the weight on the driver side tires and the weight on the passenger side tires, 1,100 pounds of difference. They haven't done any mods. While they are under GAWR on each axle, under GVWR, and with a 23% pin weight, their fifth wheel is just lopsided. He talked to a well-known trailer suspension manufacturer and they said it's not uncommon for that brand to have a half-ton difference from one side to the other.
When you do a CAT Scale weighing and divide by two you are seeing the average weight on each corner, not the per-corner weight. That means one side of an axle has a tire (or tires) that likely is underinflated for the actual weight being supported 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.
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In closing, we're all used to replacing tires when the tread wears down and 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 equate our car tire experience with an RV may turn out...poorly.
FWIW.
Ray
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