How to read a tyre sidewall
Every number and letter on the sidewall means something specific. Here's how to decode a marking like 205/55 R16 91V.
A tyre sidewall carries a compact code that fully specifies the tyre — width, profile, construction, rim size, load capacity and maximum speed rating. Once you know how to read it, it's the fastest way to check you're getting a correct, legal replacement, and it's exactly what's needed when requesting a quote or a mobile fitting.
Breaking down an example: 205/55 R16 91V
205 is the tyre's width in millimetres, measured sidewall to sidewall. 55 is the aspect ratio — the sidewall height as a percentage of that width, so a lower number means a lower-profile tyre. R stands for radial construction, the standard for almost all modern car tyres. 16 is the rim diameter in inches the tyre is built to fit.
91 is the load index — a coded number (not a direct weight figure) representing the maximum load the tyre can carry at full inflation. V is the speed rating, a letter code for the maximum speed the tyre is rated to sustain. Both the load index and speed rating need to match or exceed the vehicle manufacturer's minimum requirement.
Other markings worth knowing
DOT date code
A four-digit code (e.g. 2324) gives the week and year of manufacture — '2324' means the 23rd week of 2024. Tyres over roughly six years old are generally recommended for closer inspection regardless of tread depth.
Run-flat markings
RFT, ROF, SSR, ZP, EMT, or a manufacturer-specific mark (a star for BMW, for example) all indicate a run-flat tyre — see our run-flat repair guide for why that changes the repair decision.
Manufacturer-specific fitment codes
Marks like N-spec (Porsche), MO (Mercedes), AO (Audi) or * (BMW) show the tyre has been approved by that manufacturer for the specific vehicle — relevant for keeping a warranty or matching OEM specification.
Tread wear indicators
Small raised bars within the tread grooves mark the 1.6mm legal minimum — when the tread has worn flush with these bars, the tyre is at the legal limit.
Frequently asked
Can I fit a tyre with a different load index or speed rating?
You can fit a tyre rated equal to or higher than the vehicle manufacturer's specification, but not lower — an underrated tyre is both a safety issue and can affect insurance validity. Always match or exceed the original rating unless a manufacturer explicitly approves an alternative.
Does tyre width or profile affect ride comfort?
Generally, a lower profile (smaller aspect-ratio number) gives sharper handling but a firmer ride, while a higher profile absorbs bumps more comfortably. Changing from the manufacturer's specified size can also affect the accuracy of the speedometer and ABS/traction systems.
What tyre size does my car need?
The correct size is on your current tyre's sidewall and usually also on a sticker inside the driver's door frame or in the vehicle handbook. Send us that size, or your registration, and we'll confirm before quoting.
Need mobile tyre help now?
Call or WhatsApp with your location, registration and tyre size — we'll confirm availability and the right next step.
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