DIAMETER OF ROAD WHEELS.

Otago Witness, Issue 2921, 9 March 1910, Page 59

DIAMETER OF ROAD WHEELS.

The size of road wheels is engaging some attention iust now, and there is no doubt but that makers are beginning to see tha advantage of larger wheels (says the Field)It is on good authority that one of tha most important firms in the industry intend to at 40in wheel? on their large* models next season, ana it will not b«. surprising to see their example followed by othe.S. Small wheels and low clearance may be traced to the influence of racing, but as our roads are not suited for speed work on corners there seems no reasoir agaii st larger wheels except that it is a little more difficult to build such a wheel of equal strength to that of a small diamtter. Apart from this, every advantage lies with tK* large wheel; less wea* occurs at the bearings, less strain is imposed on the tyres, less vibration is set up, anc tractive effort is reduced. In case it may not be clear hew a larger wheel reduces vibr;/i : on and * power . absorption, the accompanying diagram will show how the difficulty of ?urmounting an obstacle is increased as the wheel diameter decreases, while the lift of the wheel and the time taken before it regains its normal position decreas3s as the diameter, which means that, instead of a long, easy movement, a shock to wheel ir caused. The larger wheel moans less flattening of the tyre to support a given weight* which in the ca.se of heavy vehicles witf mean less road damage, while the increased clearance given will reduce the amount of dust raised apreciably. For rough worW the large-diameter wheel is essential, and for the uses to which the American motorbuggy type of vehicle is put a 'mall wbeej would be out of the question. On thes< cheap cars with largt- wheels it is possible to use solid tyres without any great sacrifice of comfort, provided the carefully designed American springing is employed.

Of course, the objection may be raiset that a larger wheel means larger and rnor« expensive tyres, but this, it must be remembered, will be more than compensated for by the reduced wear, and also by th< •feet that tyres of slightly less section could be used.

The jsq of 40in wheels will undoubtedly, make for the improvement of the touring car, and if the raising of the centre oi gravity means that speed work on corners will be a more dangerous pastime than at present, who will grumble? Now that we are becoming more "staid, and use our cars for other purposes than merely getting <from place to place n the minimum tim« there- is really nothing to be gained by adhering to the low-built chassis, the product of road racing, vvhich, however beneficial to the improvement of material and design, has never done anything toward} increasing comfort.