All control questions / Tyres

Control questions about tyres

Tread depth, tyre pressure and damage: how to check the tyres before driving.

1. How do you check that the tyres have the correct tread depth?

   No colour may be visible, and the tread pattern must be visible. 1.6 mm tread depth in the middle of the tyre.

   The legal minimum is 1.6 mm of tread depth. Many tyres have wear indicators in the grooves that show when the limit is reached. With less tread, braking distances get longer, especially on wet roads.

   How to show it on the car:

   1. Find the wear indicators in the main grooves – small bumps at the bottom of the tread.
   2. Check that the tread is deeper than the indicators, i.e. at least 1.6 mm.
   3. Check across the whole width of all four tyres.

2. How do you check that the tyres have the correct tyre pressure?

   I measure the pressure with a tyre gauge while the tyres are cold and compare it with the car's recommended pressure.

   The recommended pressure is usually printed in the door frame, inside the fuel flap or in the owner's manual. Low pressure means less grip, longer braking distances and higher fuel use. Many cars also show a warning light if the pressure is too low.

   How to show it on the car:

   1. Find the recommended pressure in the door frame, inside the fuel flap or in the owner's manual.
   2. Measure with a tyre gauge on the valve while the tyres are cold.
   3. Add or let out air until the pressure is right.

3. How do you check whether the tyres are damaged?

   Inspect the tyres visually for damage such as cracks, bulges or unusual wear.

   Cracks and bulges weaken the tyre so it can burst while driving. Uneven wear can mean the wheels are misaligned. A damaged tyre must be replaced.

   How to show it on the car:

   1. Walk around the car and look at the sidewalls and tread of each tyre.
   2. Look for cracks, bulges, cuts and nails or stones in the tread.
   3. Check whether the wear is even across the tyre.

4. May the front and rear wheels have different types of tyres?

   No

   All four tyres must be the same type, for example all summer tyres or all winter tyres. Different tyre types give different grip front and rear, which can make the car unstable.

5. What should you check if the car has a spare wheel?

   That the spare wheel has the correct tyre pressure and that you know where the tools and jack are.

   The spare wheel slowly loses air even when not in use. Check the pressure regularly. A space-saver spare typically has a speed limit of 80 km/h and may only be used temporarily.

6. How can you tell how old the tyres are?

   The DOT number on the sidewall has four digits: the first two are the week, the last two are the year.

   The DOT code is on the sidewall. For example, "2419" means week 24 of 2019. Tyres age even when not in use – the rubber hardens and loses grip. Most experts recommend replacing tyres after 6–10 years.

   How to show it on the car:

   1. Find the DOT number on the sidewall – it is usually after the letters "DOT".
   2. Read the last four digits and explain what they mean (week and year).