Speed and Tyre Wear

New Zealand Herald, Volume LXXVI, Issue 23263, 4 February 1939, Page 14 (Supplement)

Speed and Tyre Wear

The effect of speed on petrol consumption is quickly brought home to ruotor drivers, owing to the frequency with which fuel tanks have to lie replenished. It is no less true that the average speed of driving has a great effect upon the mileage that may reasonably be expected from a tyre, although the signs and rate of wear of tread are not so obvious as is the consumption of petrol. Actually the modern weftless cord pneumatic tyre is a splendid product, and if properly looked after, gives a long and trouble-free life. The length of that life is, however, a matter which is within the control of the driver, as he is responsible not only for correct inflation of tyres, but- also for the speed at which his vehicle travels. No better illustration of the effect of speed on tread wear is provided than the short life of tyres on racing machines in long distance contests, during which high speeds are reached. Tyres that would normally run anything from 15,000 to 20,000 miles are worn down to the cord casing in anything from 100 to 150 miles of travel. In a lesser degree, there is even a wide difference between tyre wear on a touring car driven under normal conditions, and those- of a fast-driven sports car. Tests in this connection demonstrated that the same amount of tread wear took place while a touring car travelled 0000 miles on the road at normal average speeds, and a sports ear covered only .'Wo miles at 90 miles an hour on a track. Fast travel on the road causes an abnormal amount of slip between the tyre and the road surface. This occurs to a degree at all times. Under normal running conditions, it is found to be about 1J per cent, but on a rough surfaced road at 60, it has boon proved to he about 4J per cent to 5 per cent, three times as much. As the rate of tread wear varies roughly as the square of the slip, it means that if the slip is trebled, as mentioned, the rate of tread wear is increased ninefold. I