INCORRECT TYRE PRESSURES

Sun (Auckland), Volume I, Issue 196, 8 November 1927, Page 7

INCORRECT TYRE PRESSURES

NEED FOR REGULAR ATTENTION

CARELESSNESS SPELLS DANGER

STANDARD tyre equipment has, during the last few- years, steadily evolved from the high pressure narrow section type to the almost general adoption of the balloon tyre. Coincident with the fitting of these larger section tyres—giving as they do a greater air capacity in relation to load—the average motorist has shown an inclination to disregard tyre pressures; he carries on so long as his equipment is not actually’ flat.

While the fact of this being possible may be all in favour of balloon tyres, yet car owners should take heed, not only of the serious risk involved in this lackadaisical practice but also in the fact of the rapid wear and tear involved, says bred Berry in the Sydney “Daily Guardian.” To illustrate the scanty attention bestowed upon tyre equipment by average owners, 11 cars of identical make, all privately owned, were tested recently as to consistency in inflation pressure. The results obtained were, to say the least, startling. How several of these cars ever managed to scramble round a right angle corner and why others had not shaken every accessoryloose is beyond comprehension. The correct pressure to be carried in the tyres of this particular make of car was, according to the maker’s chart. 241 b to square inch on front wheels and 281 b on the rear. The first car examined had 111 b in left front and 171 b in right front. Rear tyres had been pumped to 30 and 321 b respectively. Even assuming that a fairly heavy Toad was normally' carried in this machine, and thus accounting for the high rear tyre pressure, the fact of the front tyres being grossly underinflated would make the steering heavy, sluggish, and dangerous on corners if any speed were attained. Briefly' analysed, tyre pressures r -n the 11 cars ranged from llih to 321 b fn the front and from 14 to 46 in the rear. In only' one instance were the whole four tyres inflated to correct pressures, and in every other case not only did the pressures vary', but no two pairs were equal. From the point of view of safety, this latter fact was the more serious, as with pairs of tyres at unequal pressure the machine is unbalanced and docs not steer precisely. Three most important factors are involved in the correct inflation of tyres: Firstly: In the safety of passengers and driver. Secondly: Comfort in riding and insulation of chassis and body from shock. Thirdly: Economy. Manufacturers of tyres provide a tube Ed cover to carry a definite load if inted. to a stated air pressure. This pressure is. however, entirely'

under me control of the owner-driver, and if he fails in his portion of the contract he should not blame the manufacturers for his own carelessness. The expenditure of a few shillings on an efficient pressure gauge, and the regular and consistent use of this instrument will not only save a lot of money over a year’s touring, but will ensure the driver and passengers* safety in an emergency. Ten minutes’ testing each week, and the purchase of a pressure gauge, represent a small enough rate for an insurance policy'. There is no excuse tor any motorist not taking advantage of it. In the older school of drivers, used as they were to high pressure tyre', differences of five pounds or so did not cause any concern. But with low pressure equipment, inflation should be accurate to a pound, and each pair Af tyres must be equal. Under-inflation will cause undue flexing of the cover walls and considerably shorten the tyre life. For although cord balloons of to-day are capable of being flexed in a manner unthought of a few years ago, yet undcr-inflation is asking too much altogether. Another point to be noted is that with tyres in this condition, an element of risk is introduced into driving which can well be eliminated. When rounding corners, especially on dirt or gravel roads, the car may “skate” in an alarming manner, and a collision or capsize be the outcome. On the other hand balloon tyres should never be pumped board hard, for the shock absorbing properties are then absent. As a consequence all road shocks are transmitted to the chassis and passengers to the discomfort of the latter and the all too rapid disintegration of the former. Further, the road wheels will bounce about in a most disconcerting fashion over bumpy road, causing the car to yaw about; and a true car's course will be difficult to steer. On top of all this, the bouncing wheels do not follow the contour of the road and as they rapidly speed up when in the air, tyres are subjected to unnecessary wear and stress. The fact must therefore be obvious to any motorist, that, by' merely spend ing a few minutes’ time each week, eight or 10 pounds may well be saved in the year’s tyre bill, and safety of all con>cerndd preserved when touring.