Tire Age: Why Old Rubber Fails Before It Wears Out

The tires on a travel trailer that sits eleven months a year can look brand new and be a blowout waiting for I-10. Same for the spare on a semi that has ridden under the frame for a decade, and for the tires on a motorhome that only goes to the beach a couple of times each summer. Rubber ages whether it rolls or not, and on the Gulf Coast it ages fast.

Here is how to tell how old a tire is, why age matters as much as tread, and which tires on a truck or RV are the ones to check first.

Reading the date code

Every tire has a DOT code molded into the sidewall. The last four digits are the date of manufacture: two digits for the week and two for the year. A tire ending in 2322 was built in the twenty-third week of 2022. The code is only required on one side of the tire, so if you do not see the full string, look at the other sidewall.

Once you know the build date, you know something the tread cannot tell you. Tire makers and vehicle makers publish age guidance, and most of it lands in the same general range of several years from the build date regardless of use, with inspection recommended well before that. The exact number is less important than the habit of knowing it.

What aging actually does

Rubber compounds harden and lose elasticity over time. Ozone and ultraviolet light break down the surface, which is the fine cracking you see on old sidewalls. Inside the tire, the bond between the rubber and the steel belts weakens. None of this shows up as tread wear. It shows up as a tread separation at highway speed on a hot afternoon, and the tire that does it often has most of its tread left.

Heat accelerates all of it. A tire that lives in the Florida sun, in a storage lot in Milton or a driveway in Navarre, is aging faster than one in a garage up north. So does sitting still. A tire that is not being flexed dries out, and the antiozonant compounds that migrate to the surface while the tire rolls stop doing their job.

Sidewall cracking that you can see from standing height, or cracking in the tread grooves, means the tire is past its useful life regardless of the date code or the tread depth.

The tires most likely to age out

• Travel trailer and fifth-wheel tires. Low annual miles, long sits, and often the cheapest tire the manufacturer could fit. These fail by age more than any other tire on the road.
• Motorhome tires. Big, expensive, and often replaced only when something goes wrong. A motorhome that has done a few thousand miles a year for seven years has old tires with good tread.
• Spares. The spare under a semi or a trailer is frequently the oldest tire on the vehicle. Check its date before you need it.
• Tires on seasonal or backup equipment. A trailer that only moves during hurricane season or a truck that sits as a backup.
• Used tires of unknown history. A used tire with good tread and a date code from many years ago is not a bargain.

Why it matters more on RVs

An RV or camper trailer is heavy for its tires, often close to the limit, and it sits. Those two facts together are why tire failures are one of the most common RV roadside calls we get on the panhandle, and why we wrote about what to do in the moment in RV Tire Blowout: What to Do When It Happens at Speed. A blowout on a travel trailer does not just cost a tire; it tears out wheel wells, wiring, plumbing, and floor. The tire is the cheap part. Checking the date before a trip is the cheapest part.

What to do about old tires

Look at the date codes on everything, including the spare. Look for cracking. If the tires are old and the trip is long, replace them before the trip rather than on the shoulder halfway through it. If you are not sure, have someone look at them. A mobile tire service call to a driveway or storage lot before a trip is a small thing compared to a call from the side of I-10. For semi and trailer operators, age is one more line on the tire management routine, and it is one that catches the spare and the backup trailer that the walkaround misses.

Frequently asked questions

How old is too old for a trailer tire?

Check the tire maker's guidance and the RV or trailer maker's guidance, and treat visible cracking as the deciding factor. Many owners replace RV and trailer tires on age alone well before the tread is gone.

Do tire covers help?

Yes. Keeping ultraviolet light off a stored tire slows the surface cracking. It does not stop the internal aging, but it helps.

Does a new tire always have a recent date code?

No. A tire can sit in a warehouse. Check the date on any new tire you buy, especially an unusual size.

Can you come check the tires on an RV in storage?

Yes. A pre-trip check, replacement of any tire that has aged out, and a pressure set are all done on site wherever the rig is parked.

Old tires on a truck, trailer, or RV anywhere on the panhandle? Call Duckett Roadside Repair at (850) 495-0366. Dispatch is answered 24 hours a day and the crew comes to you.