In the past the majority of trucks have been equipped with wood wheels. These gave good service, but the results demanded under strenuous modern conditions seem, the author states, to make the substitution of steel wheels on medium and heavy-duty trucks imperative. Truck engineers and builders seem to recognize the fact, but to hesitate to make the change, chiefly because a metal wheel is somewhat higher in first cost and because some designs have not as yet rendered the service expected of them. The service return of metal wheels is given from the records and reports of the London General Omnibus Co. and the Fifth Avenue Coach Co., both of which use steel wheels exclusively. The added mileage is in excess of wood-wheel service and exceptional tire mileage is shown.The author states briefly the arguments for the hollow-spoke, hollow-rim, the hollow full-flaring spoke and the integral-hub metal wheels. Semi-flaring or broad sweeping curve attachment of the spoke to the rim is advocated. The trouble with crystalline formation at the angles between the spokes and the rim and its remedy and other manufacturing problems are mentioned.Two tables give information on the weights of four types of metal wheel, the results of strength tests of metal wheels and the strength of wood and metal wheels.