Before replacing tires on a vehicle, it is important to familiarize yourself with the equivalency system to avoid unpleasant surprises during the roadworthiness inspection (ITV).
Official documents specify the parameters by which tires are considered interchangeable and can be used as replacements for the originals. The key is to ensure that the new tires comply with the sizes approved by the manufacturer for the specific car model.
However, replacing tires is prohibited if it could cause mechanical interference or other issues with the vehicle, even if the tires are considered equivalent.
The main requirements for equivalent tires include: the load index must not be lower than the minimum indicated in the technical passport and at inspection; the speed index must also meet or exceed the recommended value; the tire diameter must not differ from the original by more than 3%; and the rim profile must match the one recommended for this model.
If the tires are not on the list of equivalent options, they can be legalized by providing a certificate of conformity from the manufacturer or an authorized technical center. Confirmation of installation from an authorized service center registered in a special registry will also be required.
The load index is a numerical code indicating the maximum load a tire can withstand at the correct pressure. It must be equal to or higher than the value stated in the vehicle’s documents. For example, an index of 105 means the tire supports up to 925 kg.
The speed index is indicated by a letter at the end of the tire marking and specifies the maximum allowable speed. For example, the letter V corresponds to 240 km/h. The equivalence table lists various categories — from N (140 km/h) to Y (300 km/h).
