Most trailer tires need replacement because of age, not tread wear. Replace them every three to five years from the manufacturing date, with six years as a hard limit, even if the tread looks new. Check the DOT date code on the sidewall, and replace sooner if you find cracking, bulges, or tread at 2/32 inch.
Why trailer tires age out instead of wearing out
A car tire usually dies from mileage. A trailer tire usually dies from time. Boat trailers, utility trailers, and campers often cover only a few hundred miles a year, so the tread barely wears. Meanwhile the rubber itself is breaking down. UV light and ozone attack the compounds, heat accelerates the process, and long stationary periods let the casing dry out and crack where it sits.
This is why the common trailer failure is a sudden blowout at highway speed rather than gradual wear: the tread looked fine, but the aged casing let go.
The replacement timeline: 3 to 5 years, 6 at most
The widely used industry guideline for trailer tires is replacement every three to five years from the date of manufacture, regardless of how much tread remains. Six years is generally treated as the upper limit. Always follow your tire manufacturer's specific recommendation if it is stricter.
Two things push you toward the early end of that window: outdoor storage in a hot, sunny climate, and heavy loads near the tire's rated capacity. The clock starts at the manufacturing date, not the day you bought or mounted the tire.
How to read the DOT date code
Every tire sold in the US has a DOT code on the sidewall. The last four digits are the date: the first two are the week of manufacture, the last two are the year. For example, 4523 means week 45 of 2023. The full code sometimes appears on only one sidewall, so check both sides. If you ever find a date code with only three digits, the tire was made before 2000 and should come off immediately.
Inspection checklist
Run through this before every trip and at least monthly during towing season. Any single "replace" signal is enough on its own.
| What to check | How to check it | Replace if |
|---|---|---|
| DOT date code | Read the last four digits (week + year) on the sidewall | Tire is past 5 years, or past 6 under any circumstances |
| Sidewall cracks | Inspect both sidewalls in good light, including the inner side facing the frame | Cracks deep enough to catch a fingernail, or any exposed cord |
| Tread depth | Use a tread depth gauge in several spots around the tire | At or below 2/32 inch anywhere |
| Bulges or blisters | Run a hand over the sidewall and tread face | Any bulge; it means internal ply damage |
| Sidewall repairs | Look for patches or plugs outside the tread area | Any sidewall repair; sidewalls cannot be safely patched |
| Flat spots | Check where the tire sat while parked; feel for vibration when towing | Flat spots that do not round out after a short tow |
While the trailer is up on the jack, look at the wheels too. On boat trailers, salt corrosion often takes the wheel before the tire. If a rim shows rust bleeding from the bead seat or lug area, browse the trailer wheels collection and confirm fitment with the bolt pattern measuring guide before ordering.
How to slow the aging down
You cannot stop rubber from aging, but you can slow it. Keep tires inflated to the pressure on the trailer placard or tire sidewall; underinflation builds heat, which ages rubber faster. Store the trailer out of direct sun when possible, or use tire covers. Park on boards or pavement rather than bare soil or grass. Move the trailer occasionally during long storage.
FAQ
The tread still looks new. Why replace the tires?
Because rubber degrades chemically whether or not the tire rolls. On low-mileage trailers the casing and sidewalls fail from age long before the tread wears down, and an aged casing can fail suddenly under load. For trailer tires, the date code is the limiting factor, not the tread gauge.
Do tire covers actually help?
Yes. Covers block UV exposure, which is a major driver of sidewall cracking on parked trailers. They slow aging rather than stop it, so the 3-to-5-year window still applies, but covered tires typically reach the end of that window in better condition.
A tire made three years ago has never been mounted. Is it still new?
Unused does not mean unaged. The clock starts at the DOT manufacturing date, so a three-year-old unmounted tire has already spent most of the recommended service window on a shelf. Check the date code before buying, and count your replacement interval from that date, not the purchase date.
Does the spare age out too?
Yes, on the same schedule. A spare mounted on the trailer tongue often ages faster than the running tires because it sits in full sun without a cover. Include it in every inspection and replace it on the same date-code timeline.
If your date codes are past the window, replace in pairs or full sets from our trailer tires lineup. Cheap2Go Tires ships free from our Florida warehouse.