How to read a tyre size marking, what load and speed ratings mean, and the checks worth doing before you call a fitter.
The numbers and letters moulded into a tyre's sidewall look like a code, but they're worth being able to read at a basic level — here's what they mean and what to check before calling a fitter.
A marking like 205/55 R16 91V breaks down into a few parts: the first number is the tyre's width in millimetres, the second is the sidewall height as a percentage of that width, "R" followed by a number gives the radial construction and rim diameter in inches, and the final code is the load and speed rating together. Your vehicle's handbook or the sticker inside the driver's door will confirm the correct specification — that's the reference to use, not a guess.
The load index refers to the maximum weight a single tyre is rated to carry, and the speed rating indicates the maximum speed it's designed to sustain. Both matter for safety, which is why a tyre should match — not fall below — your vehicle manufacturer's specified rating. We wouldn't recommend a specific rating without seeing your vehicle's own requirements first.
Tyres also carry a DOT code ending in four digits — the first two give the week of manufacture, the last two the year. This tells you how old a tyre is, which is useful context, but age alone doesn't tell you whether a specific tyre is safe or unsafe. A well-stored, lightly-used older tyre can be in better condition than a younger one that's seen harder use — the date code is one piece of information, not a verdict on its own.
Tread depth, visible cracking or bulging, and correct pressure are all worth checking regularly. By law, tyres need at least 1.6mm of tread across the central three-quarters of the tyre, around its entire circumference — driving below that risks a fine of up to £2,500 and 3 penalty points per illegal tyre. That's a legal minimum, not a target to wait for.
Sidewall markings and date codes give you useful background, but they don't replace an actual inspection. Your vehicle handbook has the specification that applies to your car, and a physical check is the only reliable way to know whether a specific tyre needs attention. If you're not sure what you're looking at, we're happy to take a look on-site.
See our Bathgate coverage page to arrange a visit.
