The last few years have seen a sharp increase in sales of second hand tyres mainly due to the economic crisis. The reason is obvious: second hand tyres are cheaper. But we must bear in mind that, as the saying goes, “you get what you pay for”. There are several reasons why it is not advisable to purchase second hand tyres.
For starters there is not current regulation advising which tyre can or not be reused in another vehicle. This lack of regulation makes it very difficult to know where a tyre comes from, how it has been kept and what is its current condition. Whereas we can easily inspect the tread pattern and depth, it is impossible to know if the tyre has any internal damage.
If a tyre has been in an accident, for instance, it could have been bashed against the metal parts of the vehicle, the tarmac, or the kerb. It could also have been exposed to very high temperatures during a fire. The type of damage that the tyre could suffer as a result, such as a deterioration of the internal fibres, will easily go unnoticed and could cause the tyre to break or deform once fixed on to another vehicle.
Dry rot in tyres
Over time, tyres, as it is to be expected, degrade and start losing their properties. This process is called dry rot. The rubber loses its flexibility and begins to crack on the surface becoming more and more brittle. A similar weakness might occur due to manufacturing defects, wrong mounting or accidental blows. As a result, the useful life of a second hand tyre is always much shorter than that of a new one. A new tyre has an average life of 40.000 km whereas a second hand one hardly ever lasts longer than 20.000 km.
If we do the maths we realise that buying second hand tyres often ends up being more expensive. Dividing the price of a new tyre by the depth of its tread in millimetres we obtain the price per millimetre. If we compare this with the same figure on a second hand tyre we will see the later is often more expensive. As it is already worn, we end up having to replace the second hand tyre much sooner, spending more money as a result.