Tyre markings explained: what 205/55 R16 91V means and how to tell a tyre's age

A tyre's sidewall tells you everything you need to know about it: its size, how much weight it carries, what speed it is built for and when it was made. Let's take the most common example: 205/55 R16 91V and the last four digits of the DOT code, 3621.

205/55 R16 91V explained

The lower the profile percentage, the lower the sidewall: steering gets sharper, but potholes are felt more and the rim is easier to damage.

Load index

A replacement tyre's load index should never be lower than the factory one, especially on an SUV or a heavy car.

Speed rating

The DOT code: when the tyre was made

The last four digits of the code that starts with DOT are the production date: the first two are the week, the last two the year. 3621 means week 36 of 2021, that is September. Tyres made before 2000 carried three digits.

How long a tyre lasts

Manufacturers recommend a yearly inspection after 5 years and replacement after 10, even if the tread still looks good. Rubber dries out and cracks over time, especially on a car parked in the sun.

Cars from auctions often arrive on 7-8-year-old tyres with tread that looks almost new. Check the DOT code on all four tyres before you buy.

Winter markings: M+S and the mountain snowflake

M+S (mud and snow) is the manufacturer's own declaration and needs no test. The three-peak mountain snowflake (3PMSF) means the tyre has passed a standard snow traction test. For the Rikoti, Gudauri or Svaneti roads in winter, this is the symbol to look for.

More on choosing and caring for tyres: Everything you need to know about tyres.

Frequently asked questions

How do I tell a tyre's age?

By the last four digits of the DOT code: 3621 means week 36 of 2021.

What does 91V mean?

91 is the load index (615 kg per tyre), V the speed rating (up to 240 km/h).

How old can a tyre be?

Inspect it every year after 5 years and replace it after 10, whatever the tread.