If you've ever looked at the sidewall of your tyre and felt confused by the row of numbers and letters printed there, you're not alone. Understanding tyre markings is genuinely useful — it means you can specify the right tyres confidently when booking a replacement, and check that what's been fitted to your car is correct.
Breaking Down a Typical Tyre Size: 205/55 R16 91V
The first number — 205 — is the tyre's width in millimetres, measured across the widest point of the tyre. The second number — 55 — is the aspect ratio, which is the height of the tyre's sidewall expressed as a percentage of the tyre's width. So a 55-series tyre has a sidewall height equal to 55% of its 205mm width. The letter R indicates the tyre is radial construction, which is standard on all modern road tyres. The number 16 is the diameter of the wheel rim in inches that the tyre is designed to fit.
Load Index and Speed Rating
The 91 in the example is the load index — a numerical code that corresponds to the maximum weight the tyre can safely carry. A load index of 91 means the tyre can support 615kg. The V at the end is the speed rating — the maximum speed at which the tyre is designed to operate under its rated load. V-rated tyres are approved for sustained use up to 149mph. You must never fit a tyre with a lower speed rating than your vehicle's manufacturer specifies, as this creates a safety hazard and may void your insurance.
XL, C, and Other Markings
XL (or Reinforced / RF) indicates an extra load tyre with a higher load capacity than a standard tyre of the same size — commonly used on heavier SUVs and people carriers. C-marked tyres (e.g. 195/65 R16C) are designed for light commercial vehicles and vans, with reinforced construction for heavier payloads. Other markings include M+S (Mud and Snow — suitable for moderate winter conditions), the three-peak mountain snowflake (certified winter tyre), and manufacturer-specific codes for run flat tyres such as MOE (Mercedes Original Extended) and ROF (Run On Flat).
When you book with Enzo Mobile Tyres, just give us your vehicle registration or your current tyre size and we'll source the correct replacement. We make sure every tyre we fit matches your vehicle's specification exactly.
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