Tire rims or metal liases and felloe hands are usually made from flat slock and rolled to shape, and the ends are welded together. Special machinery is used for this purpose and each hand or base must check within certain limits. Demountable rim parts an made in a similar manner and must also be held within certain limits.
A number of illustrations are shown herewith, which give the contour and general construction of the solid tire. The Firestone wired-on tire is made and recommended fur use on light vehicles only. This tire is not manufactured into the rim as is the hard rubber base type, but is afterwards attached to the rim. Into the base of the tire are placed stout cross wires at frequent intervals. When this tire is placed on a channel rim it sheld in place by two circumferential wires, one at each side of the tire, these wires resting upon the ends of cross wires, by virtue of which the tire is retained on the rim. Swinehart manufactures what is called a soft-base tire, with cross wires for holding it in the channel rim. Several other makers also manufacture tires which are retained by cross or cir-cumferential wires.
The hard rubber base tire as previously mentioned is built onto the rim at the tire factory. This type of tire is being made by Goodrich, Firestone, Goodyear, United States, Republic, Kelly-Springfield, Gibney, Swinehart, Hood, Polack, etc., in the single and dual, pressed-on and by some in the demountable types, some of which are illustrated.
These various makes differ in the contour of the tire, the method of producing a firm grip for the hard rubber on the steel and the method of building up the tire, while the demountables differ in rim construction. In some cases the metal base is cut in dovetail fashion and with grooves, such as the Hood, Polack and Goodrich. In the Gibney and Kelly, the hard rubber is carried up to the side of the metal base, while in others it is set straight across the width of the channel base. In some cases the layer of hard rubber is given an irregular wave line surface such as the Goodrich in order to increase the area of contact between the two grades of rubber.
The metal base or rim of a demountable tire has the inner circumference tapered from both sides, its smallest diameter being slightly larger than the outside diameter of the felloe band. Rings which have a tapered surface and are usually termed wedge rings, since their cross section is of wedge shape, (ire inserted between the felloe band and the tire base. These are retained by circular flanges and bolts which pass through these and the felloe of the wheel.
Fig. 267. Republic Side- Flange Type Tire.
Fig. 268. Republic Pressed-on Type Tire.
Fig. 269. Goodrich DeLuxe Pressed-on and Demountable Types.
Fig. 270. Polack Pressed-on Type Tire.
Fig. 271. Kelly-Springfield Demountable Type Single and Dual.
Most tire manufacturers use this construction; however, the Goodrich demountable differs somewhat in that the wedge section is incorporated in the tire base against which the side flanges press. The rubber portion of a solid tire is usually about 2 3/4 ins. high and varies in width according to its design. This, of course, governs the elasticity and cushioning effect. On the large single tires, this height does not give a proper proportioning and to overcome this some makers produce what is commonly called the European type of tire, in which the rubber is from 1/2 to 1 in, higher. The Goodrich Co. calls this their De Luxe type and while it is designed after the European type, it has quite a different contour. Greater resilience is claimed for these types as well as longer life and greater load carrying capacity. A greater carrying capacity is possible, because the contact with the road surface is much larger, consequently the weight is distributed over more base area. The greater height of rubber and increased resiliency also give an entirely different traction hold on the road.
Some tire makers recommend this type of tire as an oversize for the American type, since it is made to fit the S.A.E. standard felloe hands.
The Goodrich Co. has recently introduced a new policy with regard to single and dual tires for heavier truck work. This company is recommending a 7-in. single in preference to 4-in. duals and 6-in. singles in preference to 3 1/2-in. duals. The arguments are that these singles give better results than the corresponding duals, in that often on the road one of the duals has to take the entire weight of the load on that wheel and that, as it is not designed to take the entire load, it is naturally overloaded and perhaps permanently injured by this frequent caring for the entire load weight on one wheel. With singles this is not the case.
Firestone has recently introduced what is known as a giant single solid tire made in 8- or 12-in. width. The extra amount of rubber is claimed to make it oversize equipment for 6-in. duals and equal equipment for 7-in. duals. The tread has three evenly spaced circumferential grooves in it.
The Hood Co. recommends its European type of tire for dual equipment, as they claim this type with its greater resiliency will allow the inside tire to compress more and allow the outside tire to take its share of the load.
The pressed-on tire will no doubt gain in popularity as it is less expensive than the demountable type, since wedge rings, flanges and bolts are eliminated, while the firm fit to the wheel also insures the greatest possible mileage. Practically all makers are continuing their demonutables, but the number produced is on the wane. This type will no doubt be continued for some time since powerful hydraulic presses the cost $500 to $700 are required to apply the pressed-on type. This, of course, is a considerable outlay for a dealer in proportion to the work he may get at present. However, the demand for trucks is continually increasing and, in order to assist the dealer in obtaining his share of the business, some tire companies are selling these presses at the rate of $100 down and $100 per year until paid for, on condition that it is used only in connection with tires made by that company.
The claim made for the European type of tire is that owing to its higher section and greater resiliency it greatly reduces the cost of upkeep of the mechanism of the truck, and makes it far more comfortable for the driver.
Fig. 272. Goodyear Demountable Type " SV" Single and Dual.
Fig. 273. Firestone's Variety of Solid Tires.
Fig. 274. Goodyear Pressed-on Type "SU" Single and Dual.
Fig. 275. Hood European and American Section Pressed Type Tires.
Fig. 276. Kelley-Springheld Pressed-on Type Single and Dual.
Fig. 277. Gibney Wireless Type "MIB" Pressed-on.