Why are my tyres wearing so quickly?
It is widely known that a vehicle’s tyres should be examined frequently, in order to gauge the depth of the tread – or, more specifically, the depth of the grooves between the tread which allow the tyres to drain. Contrary to popular belief, the word‘tread’ does not actually refer to the grooves, but the area of the tyre which contacts the road.
In the UK, the legal minimum tyre tread depth is 1.6mm, but it is strongly recommended that tyres with less than 3mm tread depth are replaced, as beneath this depth, we see a rapid lengthening of braking distance.
But why does this happen?
Fans of motorsports such as Formula 1 will know that hot, drytracksoften call for ‘slicks’ which are smooth tyres, without any grooves in them at all. Slicksgrip better, as a greater surface area is in contact with the tarmac. But what happens when it rains? They all come into the pit area for a tyre change, because slicks on a wet track will cause a dramatic loss of grip.
This is because of a phenomenon known as aquaplaning. When the bald tyre rolls over a body of water, its surface is no longer in contact with the road – it will slide uselessly, without any traction. The grooves on a tyre eliminate this by providing the necessary space for the water to drain away. If these grooves are not sufficiently deep, then the water will not be able to drain away quickly enough. If the tyres are sufficiently worn, then this can occur with substances rougher than water, such as fine sand and gravel.
Possible problems with tread depth.
It is not always clear, at a glance, whether a tyre needs changing. Tyre manufacturers offer indicators to help with this. If you look at the grooves of the tyre, you might see little protruding bars within the groove. These are to indicate changes in tread depth. If the tread is level with (or nearly level with) these bars, then it is time to have it replaced.It may also indicate other problems with the car that will need addressing, particularly if the tread is wearing inconsistently.
If one edge (or ‘shoulder’) of a tyre is more worn than another, this is a strong indicator that the wheels are not properly aligned; specifically, that the camber is not neutral. What this means is that the wheel is not entirely parallel to the car, but at a slight angle, with the bottom of the wheel slightly offset to the top. This may be done deliberately, in order to improve a car’s handling around corners, but it will result in one side of the tyre wearing more quickly, as it spends more time in contact with the surface of the road.
Just as inconsistent wear can be caused by a wheel’s camber falling out of alignment, so too can it be caused by the toe. The toe is the same as the camber, but it refers to the alignment along a vertical axis rather than a horizontal one. So if you were to visualise a bird’s eye view of the car, then mentally angle the tyres inwards or outwards, then you would have an idea of the toe. ‘Toe’d in’ wheels point inward, towards one another, while ‘toe’d out’ wheels point outward, in the other direction.
The toe can alter the handling of the car, since it can cause the tyres will put pressure on one another. This may or may not be desirable, but one possible side effect is definitely undesirable: it may causes the wheels to vibrate laterally, resulting in inconsistent wear on the tyres.
Inflation issues, unlike those brought about by incorrect alignment, are indicated by differences in wear between the sides of the tyre and the centre. If the tread on the edges of the tyre is more worn than at the centre, then this would indicateunder inflation, while if the tread at the edges is less worn than at the centre, then this would be due to over inflation.
Scalloping is a phenomenon which is apart from uneven tread wear, where the ‘blocks’ of tread on the tyre are uneven. Some may be higher than others. This means that, as the tyre rotates, the contact with the surface will be inconsistent, as the tyre is not fully round. Running a finger over the surface of a scalloped tyre highlights the problem. This is not really a safety concern, but it definitely is one of noise; an enormous racket will result from the uneven surface of the tyre beating against the road. This problem is caused by incorrect camber alignment.Correcting the camber might correct the scalloping over time, if caught early.
Should you notice the early signs of any of these problems, then you would be advised to ensure that your tyres are properly inflated. Following that, the best course of action would be to visit a qualified mechanic and have alignment issues properly addressed. This can often be expensive, but fortunately there are sites like mycarneedsa.com, who also allow users to compare a variety of MOT and service deals.