RV Tire Age Calculator: Read the DOT Code and What It Costs You

The last four digits of the DOT code are the week and the year your tire was made — 2419 is the twenty-fourth week of 2019. That part every decoder does.

Here is the part they leave out: the warranty runs five years from that date code, not from the day you bought the tire. A tire that sat in a warehouse for two years reaches you with three years of cover left, and the price on it is the same either way.

How to read the code

The Tire Identification Number is moulded into the sidewall, and the date is the last group. 49 CFR 574.5 sets the format:

The date code, consisting of four numerical symbols, is the final group.

The first two symbols are the week, the last two the year. The regulation gives its own worked example: “0109 means the tire was manufactured in the first full calendar week of 2009.”

The clock starts before you own it

This is the finding, and it comes from the warranty page of the company that supplies the tires.

Lionshead — named as the tire supplier in Grand Design’s Imagine owner’s manual — warrants its ST tires “for a period of five (5) years from the manufacturer’s date code on the tires.” Not from purchase. Not from registration. From the date moulded into the rubber.

The exclusion is blunter still:

ANY TIRES WITH A MANUFACTURER’S DATE CODE THAT IS OLDER THAN FIVE (5) YEARS FROM THE DATE BUYER DELIVERS WRITTEN NOTICE TO SELLER … are not covered.

Grand Design’s own warranty table agrees from the other direction: “Five year limited warranty from the tire manufacture date”, with a separate “no fault 12-month limited warranty from the date of purchase” sitting alongside it.

What the cover is actually for

Read Lionshead’s list of covered defects and the shape of the problem becomes obvious. It covers “tread separation, sidewall bulges, tread cracking, broken belts, material sidewall cracking.”

Every one of those is what an old tire does. Trailer tires rarely wear out — they sit in sunlight carrying a parked load, and they fail from the sidewall outwards with most of their tread still on. So the warranty covers the age-related failures, on a term that expires by age. The cover runs out as the risk arrives.

That is not an accusation of bad faith; five years is a normal term. It is simply the fact that decides whether a cracked sidewall is a claim or a bill.

How old is too old for RV tires?

Nobody who makes these trailer tires will say — and that gap is the answer.

Search the question and you will be told five years, six or seven. BlackSeries, a trailer maker, calls it a “5-year inspection rule” and a “7-year replacement rule”, credited to “tire manufacturers and RV safety experts” without naming one. None of those numbers appears in a document from any manufacturer in our records. Lionshead publishes a warranty term. Grand Design publishes a warranty term. Neither publishes a service life.

One tire maker does publish a figure, for a different tire. Michelin’s technical bulletin on RV and motorhome tires says any tire 10 years or more from its date of manufacture, spares included, should be replaced “even if such tires appear serviceable”, and that tires in use for 5 years or more should be inspected by a specialist at least once a year. That covers Michelin’s motorhome tires, not the trailer tires in these records. The same Michelin documents set motorhome tire pressure, which our tire pressure calculator works out from scale weights.

What the date code cannot tell you is the rest of it: inflation history, tread depth, uneven wear from a bent axle, or the UV damage you can see by looking. A tire can be finished at three years and fine at six, and the code speaks to neither.

What to look for while you are down there

You are already crouched at the sidewall to read the code, so check the tire against the same list the warranty covers. Lionshead’s covered defects double as the inspection:

• Tread separation
• Sidewall bulges
• Tread cracking
• Broken belts
• Material sidewall cracking

Those are Lionshead’s own terms, in its order. We have not added descriptions of what each looks like, because none of the documents we read gives one — if you are unsure what you are seeing, that is a question for a tire shop rather than for this page.

Any of those inside the five years is a warranty claim, and Lionshead wants written notice within seven days of finding it. Any of them outside it is the tire telling you what the date code could not.

If this ends with the wheel coming off, it has to go back on to a figure, not to feel. Trailer lug nut torque runs from 60 to 170 ft-lb depending on your stud size — and the two big axle makers publish figures that do not always overlap — then wants re-torquing at 10, 25 and 50 miles.

DOT date code examples

Worked the same way the calculator works — the week counted from the start of the year, and the warranty running five years from that date:

Last four digits	Made	Lionshead cover ends
0109	First week of January 2009	January 2014
2419	Week 24 — June 2019	June 2024
3022	Week 30 — July 2022	July 2027
5023	Week 50 — December 2023	December 2028

0109 is the regulation’s own example from 49 CFR 574.5. The warranty column applies to tires sold under Lionshead’s terms; other suppliers set their own.

What the sizes carry

Model	Size	Load range	Max load	Max pressure	Warranty runs from	Buy
Westlake ST205/75R15 LRC	ST205/75R15	Load Range C	1,820 lb per tire	50 psi cold	Five years from the manufacturer's date code, not from the date you buy it	Check price(opens in a new tab)
Westlake ST205/75R15 LRD	ST205/75R15	Load Range D	2,150 lb per tire	65 psi cold	Five years from the manufacturer's date code, not from the date you buy it	Check price(opens in a new tab)
Castle Rock ST205/75R15 LRC	ST205/75R15	Load Range C	1,820 lb per tire	50 psi cold	Five years from the manufacturer's date code, not from the date you buy it	Check price(opens in a new tab)
Castle Rock ST225/75R15 LRD	ST225/75R15	Load Range D	2,540 lb per tire	65 psi cold	Five years from the manufacturer's date code, not from the date you buy it	Check price(opens in a new tab)
Westlake ST225/75R15 LRE	ST225/75R15	Load Range E	2,830 lb per tire	80 psi cold	Five years from the manufacturer's date code, not from the date you buy it	Check price(opens in a new tab)

Two things worth reading out of that. The last column is the same for every row — every one of these runs its warranty from the date code. And the Westlake and Castle Rock ST205/75R15 Load Range C publish identical figures: 1,820 lb at 50 psi. Where two lines from one supplier are the same on paper, the date code on the tire you are handed is the thing left to compare.

Where this goes wrong

1. Reading the wrong sidewall. The full code is required on one side only. No code visible usually means the marked face is inboard.
2. Assuming new stock is new. The commonest and most expensive mistake on this page. The tire was made when it was made.
3. Buying up a load range to fix an age problem. A stiffer tire at a higher pressure does not age more slowly. If the tires are old, buy new ones in the rating you actually need — the calculator recommends the smallest that carries your weight for exactly this reason.
4. Using the dry weight for the per-tire figure. Axle weights come from a scale with the trailer loaded. The towing payload calculator covers getting those numbers honestly.

Questions worth answering