On this page
What is the legal tread limit?
For cars, the legal limit is a tread depth of 1.6 mm, under the Italian Highway Code (Article 79) and EU rules. Below this threshold the tyre is no longer legal.
The limit applies to the main grooves of the tread. A tyre can be below the limit in one place and not in another if the wear is uneven: that is why it should be checked across the whole width and at several points around the circumference.
How do you measure tread depth?
The most accurate way is a depth gauge (or tread depth gauge), inserted into the main grooves.
- Park on level ground and, if needed, turn the front wheels to see them better.
- Insert the gauge's probe into a main groove, avoiding the wear indicators.
- Read the value and repeat in the centre and near both shoulders.
- Measure at at least three points around the circumference.
- Always go by the lowest value you find.
If you find very different values between the centre and the shoulders, read uneven tyre wear.
What are tread wear indicators (TWI)?
Tread wear indicators, known as TWI, are small raised bars of rubber at the bottom of the grooves, 1.6 mm high: when the tread wears down to their level, you have reached the legal limit.
To find them, look on the tyre sidewall for the "TWI" mark or a small triangle: it shows where the bars are along the tread. If the tread is flush with the indicators, the tyre must be replaced.
Why is it better to change tyres before the limit?
It is better to change them sooner because the grooves are there to clear water: as the tread wears down, its ability to drain decreases and braking distances and the risk of aquaplaning in the wet increase.
- In the wet, the difference between a new tyre and one close to the limit is significant: read aquaplaning: what it is and how to avoid it.
- For winter tyres, depth is also crucial on snow and mud.
- A thin tread is more exposed to punctures and cuts.
That is why many manufacturers and technicians advise not waiting for the legal limit: decide for yourself, based on how you use the car and the climate.
Tread is not the only criterion
A tyre may still have enough tread yet need replacing because of age or damage: depth is only one of the criteria.
- Age: the rubber compound ages even with little use; read how often to change your tyres.
- Damage: cuts, bulges on the sidewall and deep cracks require replacement (see a bulge in the tyre).
- Roadworthiness test: the condition of the tyres is among the items checked, as we explain in tyres and the roadworthiness test.
Bald tyre and a puncture in Milan?
A badly worn tyre punctures more easily and is generally not worth repairing. If you are stuck with a flat tyre in Milan or its province, SOS Tyre comes out 24/7, in 30 minutes on average, to wherever the vehicle is.
We can fit your spare wheel or assess the tyre; in an emergency, supplying a new tyre is arranged on the phone depending on size and availability. If instead you want to schedule the replacement of worn tyres, you can book a tyre change at your home. Call +39 377 326 0999.
Frequently asked questions
Does the 1.6 mm limit also apply to winter tyres?
The legal minimum for cars is 1.6 mm for all tyres. For winter tyres, however, tread depth has a big impact on grip on snow and mud, so many manufacturers recommend replacing them well before reaching the limit.
Does the legal limit apply to motorbikes and vans?
This guide refers to cars, for which the limit is 1.6 mm. For other categories, such as mopeds, the Italian Highway Code sets different values. If you ride a motorbike or drive a vehicle other than a car, check the specific value for your vehicle category.
Can I measure the tread with a coin?
A coin can give a very rough idea, but it is not a measuring tool. To know whether you are above or below 1.6 mm, use a tread depth gauge, which is cheap and easy to find, or check the TWI wear indicators in the grooves.
Do front tyres wear faster than rear ones?
On many front-wheel-drive cars, yes, because the front wheels steer, transmit the power and take most of the braking. That is why you should measure the tread on all four wheels rather than inferring the state of the fronts from the rears.