A tyre can have deep tread and still be old. It may have sat on a warehouse rack, spent years as a little-used spare or covered so few kilometres that the owner never looked closely at the sidewall. That is why the date code belongs in a tyre purchase and service conversation alongside size, load rating, pressure and visible condition.
The code is simple once you know where to look. Michelin's tyre-marking guide explains that the final four digits of a date code identify the week and year of manufacture. A code ending 4714, for example, means the 47th week of 2014. The full date marking may be easier to see on one side of the tyre than the other, so inspect both sidewalls if it is not visible on the outside.
Manufacture date is not installation date
Write down when each tyre was made and when it was fitted to the car. The two dates answer different questions. A properly stored new tyre made several months earlier is not automatically defective; a tyre fitted yesterday can still be much older than expected. Ask the seller to show the date code on all tyres before installation, especially if a heavily discounted set has been on the shelf for a long time.
Look at the actual tyre, not a sample displayed at the counter. Check all four tyres and the spare. A new set may not have identical manufacturing weeks, but the dates should be disclosed and consistent with what you agreed to buy. Keep a photograph of the sidewall and the invoice. If the code is on the inner side after fitting, a photo taken before mounting saves a difficult inspection later.
Age is one part of the decision
Tyre compounds and internal materials change with time, exposure and use. Heat, sunlight, ozone, storage conditions, underinflation and load all matter. A date code cannot tell you whether a particular tyre is safe, just as a fresh date cannot excuse a bulge or cut. The US road-safety agency NHTSA notes that tyres become more prone to failure as they age and urges owners to watch physical condition and changes in performance, not only tread depth.
Michelin recommends professional inspection at least annually after five years of use and replacement as a precaution after ten years from manufacture, including the spare, in its published guidance. This is Michelin's advice, not a universal legal expiry date for every brand and vehicle. Your vehicle maker or tyre maker may set a different recommendation. Follow the more relevant instruction for your combination and ask a qualified professional when there is doubt.
Do not wait for a calendar threshold if there is damage. A sidewall bulge, exposed cords, deep cracking, a cut, persistent pressure loss or unusual vibration needs prompt inspection. The visible tread surface can look healthy while the sidewall or inner structure has suffered. Tyres that ran while flat or heavily underinflated deserve a professional internal check, even if a plug stopped the leak.
Remember the spare nobody uses
The spare can be the oldest tyre on the car because it rarely wears down. Check its date, inflation pressure, sidewall and storage condition before a long drive. A full-size spare that is very old should not quietly become a regular replacement tyre simply because it has unused tread. NHTSA specifically warns that spares are prone to ageing and should generally be used only for emergencies when the regular tyres are worn.
Some cars carry a temporary spare with speed and distance restrictions; others have a sealant kit instead. Read the label and owner manual. The date code exercise is a good moment to confirm what your car actually has and whether the tools are present. A perfect set of four tyres will not help if the emergency tyre is flat and its wheel bolts cannot be removed with the kit in the boot.
Buying a used car? Check for mismatched stories
Compare tyre dates with the seller's account of ownership and recent maintenance. A mixed set is not automatically bad, but it raises useful questions: was one corner damaged, were two tyres replaced after a puncture, or has the car done more kilometres than the odometer suggests? Tyre dates alone cannot prove mileage tampering. They can tell you where to ask for invoices and where a mechanic should inspect suspension, alignment and previous repairs.
Check the tyre size, load index and speed rating against the vehicle manufacturer's specification as well. An apparently fresh tyre of the wrong specification can be a worse choice than an older correct tyre awaiting planned replacement. Do not make a sidewall-date check the only step in a used-car inspection.
At the tyre shop
Ask to see the four date codes and the exact model of tyre before the old set comes off. Verify the invoice lists size and quantity, and ask the fitter to set pressures to the car's placard rather than a generic number. After fitting, check wheel balance and the direction of any directional tyre. Drive gently at first and return if there is vibration or a pull. The useful habit is to know the tyre's age, record it and inspect its condition over time, not to invent a single expiry day for every car.
