Tire companies assure that buying used rubber is dangerous. And there is a reason for this – you will get a more or less worn tread, sometimes even uneven, possibly old rubber and it is possible that the damaged frame. In a word – a lottery, where the prize can be crutches or worse.
But there are situations when you can use used tires. For example, you buy them from reliable friends, you know that they drive carefully, and they also say that this set of rubber has passed the pits and stones. And most importantly, we regularly install used tires every year … our own – after seasonal storage. And to check them before the installation, though strangers, even their own, still have to. And we will do this in several steps.
We measure the residual depth of the tread
Let’s forget the old recommendations that the minimum depth of the tread can be from 1.6 mm. It’s just that the ride around the yard. In fact, the tests proved that the safe minimum for summer tires is 3 mm, and in winter 4 mm. First of all, we are talking about the adhesion on the water film during the rain. It is clear that the deeper the drainage channels, the faster the water is removed from the contact spot. At a speed of 80 km / h, this figure is approximately 25 liters per second for one wheel. Do not forget that the results of test tests in automotive publications are relevant for new tires, so your used tires, even a well-known brand and popular model, are no longer capable of the claimed performance. To measure the depth of the tread, simple plastic probes with a scale are sold, you can do this with a conventional ruler.
We look at the uniformity of wear
As we have already said, wear can be uneven, so we measure the depth of the tread on the “bald” section itself, and on each tire from the kit. And now we evaluate the causes of wear. If more “bald” shoulder area from both sides (which is more often), then the pressure in the tire was constantly below the recommended one. From such tires, wait for the deterioration of the lateral clutch. That is, you have to control the speed in the corners, so as not to fly out. The worn out central part of the tread says that the tires were constantly pumping. For this, you will have to pay for the lost brake dynamics, the worst acceleration and controllability. The cause of uneven wear can also be the wrong wheel alignment and suspension defects.
Estimate the condition of the coupling edges
Tires cling to the asphalt as the entire plane of the blocks of the tread, and especially their edges and edges of the lamellas. Pay attention – the more they are erased, skewed, the less edge effect, and therefore, for effective braking, especially on wet asphalt, you can not count.
Check the general condition of the rubber
The rubber compound ages even over the years even in the warehouse, and in real operation this process is faster. Molecular bonds are lost, individual components are regenerated, and the strength of the tire gradually decreases. Officially, tire companies usually give five years of warranty for the life of the tire from the date of its release, then claims for its quality are not accepted. However, during this time the tire with a regular ride will have time to be worn out and go to waste. Another thing is if the tire is stuck in the seller, and then in the garage of the owner – here and with a poorly-seen tread, there may be hidden troubles. Loss of strength threatens tire rupture, and this is more likely to happen at high speed, when the mechanical loads are high and the heating of the tire itself is increasing. Therefore, pay attention to the emerging microcracks, a change in the usual color of rubber, it may become less dense to the touch.
Looking for visible external defects
About the punctures, cuts and traces of repair and so everything is clear – if there is, the tire should be put aside. And now you need to make sure that there are no hidden damage to the frame, which can be obtained with a strong impact on the stone or curb, as well as when the machine was standing for a long time (or worse) on flat tires, or the tires were stored as if they were, Some utensils. It manifests itself in the form of jams, creases, blisters and dents. If the frame is damaged, then breaking the tire is only a matter of time. And like in the previous chapter, this is most likely to happen in a high-speed motion …
… and now – internal defects
The causes of the flaws are the same. Only to them defects of a design are still added. The tire in the section is similar to a “sandwich” made of layers of rubber and cord, where the inner surface of the tire is usually a sealed layer that does not allow air molecules to pass through. We are interested in the absence of signs of stratification, as well as other damages. Of course, to recognize hidden defects without special equipment sometimes is beyond the power of even the former tire-changer. But you should be alerted to unusual swellings and bulges on the inner smooth layer, as well as loose areas, and, of course, obvious layer breaks and repair traces, patches and fungi that are invisible from the outside. The creases and jams of the cord also sometimes appear prominently on the inner surface.
In conclusion, it should be noted that all doubts should be interpreted in favor of buying a new set of tires. If we talk about savings, it’s better to have a fresh “state employees” than a fairly second-hand “premium”.