How old is too old? Reading the DOT date code and tire age limits

Every US-market tire carries a four-digit DOT date code that tells you the week and year it was manufactured. Here is how to read it, what the industry and major manufacturers say about age limits, and when to refuse to install a tire even if the tread looks fine.

Tread depth is a wear measurement. Age is a chemistry measurement. A tire with 9/32" of tread that has been sitting in a warehouse for nine years can be more dangerous than a tire with 6/32" that has been on a daily-driven car for two years, because rubber compounds oxidize and lose elasticity from the inside whether or not the tire is in use. The DOT date code on the sidewall tells you which clock you are actually reading.

Reading the four-digit DOT code

Federal Motor Vehicle Safety Standard 119/139 requires every tire sold for use on US public roads to carry a DOT serial number molded into the sidewall. The full string starts with the letters DOT and runs 10 to 13 characters. The last four digits are the production date: the first two are the week (01 to 53), the last two are the year. DOT XXXX XXXX 2724 means the 27th week of 2024 — roughly the first week of July 2024.

On most consumer tires, the full DOT string only appears on one sidewall (the inboard side when mounted). Manufacturers are allowed to mold an abbreviated version (without the date code) on the outboard sidewall. If you cannot find the date code, the tire is probably mounted with the dated side facing the vehicle — you can read it from underneath, or have the installer flip the tire to inspect before they balance it.

Tires manufactured before 2000 used a three-digit week+year code (e.g., 367 = 36th week of 1987, or 1997, depending on context). Any tire still carrying a three-digit code is at minimum 26 years old and should not be in service under any circumstance.

What the industry actually says

There is no federal rule that tires expire at a specific age. The recommendations come from manufacturers and trade bodies, and they cluster in a clear range:

• Six years from date of manufacture — Bridgestone, Continental, Michelin all recommend a thorough inspection at this point and replacement consideration regardless of tread depth.
• Ten years maximum, regardless of tread or condition — Bridgestone, Continental, Michelin, and the US Tire Manufacturers Association are aligned on this as a hard ceiling. After 10 years from the molded date code, the rubber's resistance to crack initiation and crack propagation has degraded enough that any tire failure becomes a sudden-failure mode rather than a gradual one.
• Five years for the spare — A spare tire that has never touched the road still ages from the moment it was molded. Most manufacturers recommend replacing the spare on the same 6-to-10-year schedule even if it has never been used.

NHTSA's tire safety guidance stops short of mandating an age limit but cites the same 6/10 year framework. Several state DMVs and rental car operators use the same numbers in their inspection criteria.

Why age matters even if the tread is fine

Tire rubber is a chemically active material. Even sitting still, it oxidizes — oxygen molecules slowly attack the polymer chains, particularly the inner liner that holds air. The carbon black and antioxidant additives in the compound slow this process but cannot stop it. After enough years, the rubber loses elasticity (you'll see fine cracking on the sidewall and between tread blocks), the bond between the steel belt and the rubber weakens, and the tire becomes vulnerable to belt separation. The visible symptom is sidewall cracking, also called weather checking or ozone cracking, but the structural weakening starts before the cracks become visible.

This is why a tire stored in a hot garage ages faster than one stored in a cool basement, why tires on a car parked outside in direct sun age faster than ones in a carport, and why winter tires stored in plastic bags in a heated garage last longer than ones piled in a corner of the shop. Storage matters. See our tire storage guide for the details.

When to refuse to install a tire

If you are buying tires online or at a closeout sale, check the DOT date code before installation. Reject any tire where the date code is:

• More than 5 years old at point of sale — the warranty clock for most manufacturers starts at date of purchase, but tread-life and roadside-hazard coverage often have an age-based ceiling that effectively voids the warranty on a 5-year-old new tire.
• Older than 6 years if the tire has been stored outdoors, in direct sunlight, or in a location with substantial temperature swings.
• Any age if the sidewall already shows visible cracking deeper than the surface gloss.

Asking the installer to verify the date code before mounting is your right as the buyer. A reputable shop will check without being asked. If they push back, walk away — that posture itself is a signal.

How to self-inspect tire age

For tires already on your vehicle: park on level ground, turn the steering wheel full lock to expose each front sidewall, and look for the DOT string on the inner sidewall (you may need a flashlight). Compare the four-digit date to today. If any tire on the vehicle is over 6 years old, get a tread-and-sidewall inspection at a tire shop. If any is over 10 years old, replace it before the next long drive regardless of how the tread looks.

By Mark Bishop · Updated 2026-05-21.