How to read a tyre manufacturing date — and why a barcode reader is different

Where is the manufacturing date and how do you read it?

Look for the date stamp on the tyre sidewall, often at the end of the DOT-related alphanumeric marking. Continental explains that the last four numbers identify manufacture: the first pair is the week and the last pair the year. Its example 4521 means the 45th week of 2021. Do not interpret it as a calendar date such as day 45 of a month.

The date identifies when the tyre was manufactured. It does not alone establish remaining service life or roadworthiness. Follow the tyre and vehicle manufacturer’s inspection and replacement guidance; this article does not invent a South African legal age limit.

Why will a barcode reader not necessarily read it?

Some devices combine barcode and OCR tools, but the OCR capability and sidewall image must be explicitly tested. A reader sold for tyre barcodes cannot be assumed to read moulded black-on-black text.

What makes sidewall OCR difficult?

The characters can be low-contrast relief on a curved dark surface. Position, orientation, surface texture and reflections change the image. Lighting must reveal the raised or recessed character shape while the fixture or conveyor presents the region consistently. The date may require a different view from the barcode.

Define which tyre sizes, mark positions and surface conditions are in scope. Test difficult examples before choosing a camera, then validate on samples not used for setup. A no-read must be logged and handled explicitly rather than filled with a guessed date.

Which task does our tyre station cover?

Our tyre barcode-reading solution covers barcode-based identification and data matching. It does not silently include DOT sidewall OCR. If your requirement is manufacturing-date reading, state that separately in the assessment and provide tyres showing the full range of moulded marks.

For character inspection principles see OCR and OCV. Use the output to support traceability, not to replace a physical tyre-condition assessment.

Find the date group before interpreting digits

A tyre sidewall contains many numbers: dimensions, load and speed markings, mould identifiers and the tyre identification sequence. A camera or a person must first locate the manufacturing-date group rather than interpreting any convenient digits as a date. Continental explains that the final four digits of the relevant date stamp identify the manufacturing week and year, with the first pair representing the week and the second pair the year. (Continental: tyre age and date stamp)

The US tyre identification requirements are documented in 49 CFR 574.5. That source explains the US regulatory context of the identification marking; it should not be presented as a South African rule setting a universal service-life limit. (US eCFR: 49 CFR 574.5 tyre identification requirements) In South African purchasing or incoming inspection, apply the customer’s documented receiving criteria and applicable local requirements separately from decoding the stamp. A manufacturing date is evidence about age, not a complete assessment of tyre condition.

Do not derive an exact manufacturing day from a week-and-year stamp. Nor does a readable marking establish how the tyre has been stored, used or repaired. Continental’s tyre-age discussion also addresses condition and maintenance. Keep those judgements separate from a camera’s ability to recognise the raised characters.

Why raised black characters need controlled lighting

The characters and the sidewall are often the same colour. Their visibility comes largely from relief and the direction of reflected light. A flat frontal light can make the raised digits disappear, while directional lighting creates highlights and shadows at their edges. Sidewall curvature, mould texture and tyre orientation change those reflections, so a successful image at one position does not establish coverage around the whole circumference.

Use a locating step to identify the relevant marking region, then read within that region. Depending on presentation, the tyre may need controlled rotation or more than one view. Opposing light directions can reveal edges hidden in the first view, but the inspection must keep the resulting images associated with the same tyre. HIKROBOT’s lighting glossary describes geometry choices; its smart-product catalogue describes OCR and recognition capabilities without establishing a tyre-specific accuracy. (HIKROBOT Light Source Catalog, 2025 Q3, glossary) (HIKROBOT Smart Product Catalog, 2025 Q4)

A hypothetical receiving check without an invented age limit

Hypothetical decoding example: a correctly located stamp ending in “4521” represents week 45 of 2021, the example also used by Continental. It does not specify a day of that week. A receiving system can store the recognised stamp, the interpreted week/year and the image for the receiving record. Whether that tyre meets a purchasing age rule is a separate comparison against the customer’s current specification. (Continental: tyre age and date stamp)

For an automated check, define what happens when the date is absent from the available view, partly obscured or ambiguous. A no-read should follow a controlled review or hold path; the system must not fill a missing field from the previous tyre. If several tyres are in the station, assign the image and result to a physical item before making any inventory update. The example is a data-control procedure, not evidence of a completed installation.

A customer rule may also depend on the receiving date or declared product family. Store the rule revision with the decision so a later audit can establish why the item passed. Do not teach the camera to reject every unfamiliar marking style without first checking whether it represents a different approved manufacturer or market. Date decoding and product authenticity are separate questions.

Build a realistic tyre sample set

Include the approved tyre families, sidewall finishes, mould variations and presentation conditions. Clean reference tyres alone do not represent permitted dust, handling marks or variations in rubber sheen. Establish which contamination the receiving process removes and which the vision station must tolerate. Test the boundary between readable and unresolved rather than forcing a digit prediction on every image.

Separate character recognition from format and policy validation in the log. A correct recognised stamp can fail a customer receiving rule; an unreadable stamp has no reliable interpreted date at all. Keeping these reasons distinct helps the receiving team decide whether to improve presentation, obtain supporting information or reject under the agreed commercial policy. It also prevents an OCR tuning change from silently changing the age acceptance rule.

Measure false reads as well as no-reads. A wrong but plausible year can be more consequential than an explicit unreadable result. Use independently confirmed reference readings and retain images of disagreements. NIST’s proportion guidance helps interpret a finite test and its uncertainty; it does not supply a universal tyre acceptance sample size. (NIST e-Handbook, 7.2.4.1 Confidence intervals for a proportion)

The related tyre-code inspection solution describes imaging and integration inputs for a project. This article explains how to locate and interpret the date group and how to separate that result from condition assessment, customer purchasing rules and traceability. None of the optical checks establishes structural integrity, remaining tread suitability or a guaranteed safe service life.

Choose the station for the mark you need to read

Keep barcode identity and the moulded manufacturing date as separate requirements. Select the view and validation samples for each before defining the line interface.