How to Read a Tyre Size (e.g. 205/55 R16 91V)

23 October 2026 · Weymouth Tyres, Weymouth

Every tyre has its size printed on the sidewall, and once you know how to read it, buying the right tyre is easy. Here is what each part of a typical size such as 205/55 R16 91V means.

The tyre size, part by part

205 – the width of the tyre in millimetres, measured from sidewall to sidewall.
55 – the profile (aspect ratio): the height of the sidewall as a percentage of the width. Here the sidewall is 55% of 205 mm, about 113 mm.
R – radial construction, which almost every car tyre uses today.
16 – the wheel (rim) diameter in inches. The tyre must match your wheel.
91 – the load index: the maximum weight each tyre can carry. 91 means 615 kg per tyre.
V – the speed rating: the maximum speed the tyre is designed for. V means up to 149 mph (240 km/h).

Common speed ratings

T – up to 118 mph
H – up to 130 mph
V – up to 149 mph
W – up to 168 mph
Y – up to 186 mph

You should never fit a tyre with a lower load index or speed rating than your vehicle's handbook asks for. It can affect your insurance as well as your safety. A higher rating is fine.

Other markings you may see

XL or Extra Load – a reinforced tyre that can carry more weight, common on heavier cars, SUVs and electric cars.
Run Flat (RFT, ROF, SSR and others) – tyres that can be driven on for a short distance after a puncture. Only fit them if your car is designed for them.
M+S – mud and snow. On its own it is a manufacturer's claim, not a winter test.
Snowflake on a mountain (3PMSF) – the tyre has passed an official snow test. You will find it on winter and many all-season tyres.
DOT code – the last four digits show when the tyre was made, e.g. 2324 means week 23 of 2024. See our guide on how old is too old for a tyre.

Where to find the right size for your car

The easiest place is the sidewall of your current tyres. You can also check the sticker inside the driver's door pillar or fuel flap, or your handbook. Some cars have different sizes front and rear, so check all four.

Not sure? Search by your registration on our tyre search and we will match the size for you, or simply book online and tell us what you need.

Getting tyres fitted in Weymouth

At our garage we fit budget, mid-range and premium tyres while you wait, with balancing and new valves included. See tyre fitting & supply for details, or call in and we will check your current tyres for free.

Common questions

Can I fit a different tyre size to my car?

Only sizes approved for your car should be fitted. Changing the size can affect the speedometer, handling and insurance – ask us before you change.

What does the load index 91 mean?

It means each tyre can safely carry up to 615 kg at the correct pressure.

Is a higher speed rating better?

You can fit a higher speed rating than your car needs, but never a lower one.