# What does the R mean on a tyre size? The R in a tyre size such as 205/55 R16 means the tyre has radial construction: its internal cords run radially across the tyre. The number after the R is the wheel diameter in inches, so R16 fits a 16-inch rim. When replacing tyres, match the full size string. Tyre sidewalls carry a string of characters that looks like a code, and in a sense it is one. Take 205/55 R16. The first number, 205, is the nominal section width in millimetres: the distance between the inner and outer sidewall. The second number, 55, is the aspect ratio, meaning the sidewall height is 55 percent of the tyre's width. Then comes the letter R, followed by a number in inches for the wheel diameter the tyre is designed to fit. References: [https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained](https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained). ## So what is the R actually telling you? R stands for radial, and it describes how the tyre is built internally rather than any external measurement. In a radial tyre, the reinforcing materials are arranged so the structure is robust in the tread area while the sidewalls stay flexible. Michelin, which developed radial technology, says this construction allows a longer tread life and reduces fuel consumption thanks to lower rolling resistance. Because radial construction is now the common type for car tyres, the R is easy to overlook, but it is part of the size designation all the same: if the construction differs, the tyres are not the same specification even when the numbers match. References: [https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained](https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained). ## A concrete comparison Imagine two tyres on a comparison site: a Michelin Pilot Sport 4 205/55 R16 94Y and a Continental EcoContact 6 205/55 R16 91V. Both share the size 205/55 R16, so both are 205 mm wide, have sidewalls at 55 percent of that width, are radial, and fit a 16-inch rim. What differs are the trailing codes: 94 and 91 are load indices corresponding to a maximum load per tyre, and Y and V are speed ratings for the maximum speed at which the tyre can carry that load. The R tells you nothing about load or speed; those are separate markings that matter just as much when choosing replacements. References: [https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained](https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained), [https://tyrescompared.co.uk/](https://tyrescompared.co.uk/). ## Other letters you might spot - P indicates a passenger car tyre, and LT a light truck tyre. - C marks a van commercial tyre. - XL, HL or Reinforced indicate a higher load capacity than normal for the dimension; Michelin advises replacing such tyres with an equivalent, for example an HL tyre with another HL tyre. - T denotes a temporary tyre for spare wheels. References: [https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained](https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained). ## What the R does not tell you It is worth being clear about the limits of the marking. The R says nothing about the tyre's brand, range, season, load rating, speed rating, or whether it meets winter performance standards; those appear elsewhere on the sidewall. It also does not tell you whether the tyre is an Original Equipment version tuned for a specific car maker, which can carry its own marking. If your vehicle was originally fitted with OE marked tyres, Michelin recommends replacements carrying the correct OE marking. References: [https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained](https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained). A practical next step: find the full size string on your current sidewall, including the R, the rim number and the load and speed codes, and use exactly that combination when comparing prices. Check the full specification before buying, and confirm today's price and fitted total with the retailer, since recorded prices change and fitting is usually extra. References: [https://tyrescompared.co.uk/](https://tyrescompared.co.uk/), [https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained](https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained). ## Sources - [https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained](https://www.michelin.co.uk/auto/advice/tyre-basics/tyre-markings-explained) — accessed 2026-10-18 - [https://tyrescompared.co.uk/](https://tyrescompared.co.uk/) — accessed 2026-10-18 Published 2026-10-18. Tyres Compared editorial; AI-assisted preparation. ## Next step - [Open tyrescompared.co.uk](https://tyrescompared.co.uk/) - [Find tyres](https://tyrescompared.co.uk/sizes) - [Explore this tyre ↗](https://tyrescompared.co.uk/tyre/205-55-r16--g03528703987703) - [⇄ Compare 0](https://tyrescompared.co.uk/compare)