Car Automotive

Posts Tagged ‘Tire’

Installation of the tire on the vehicle is the final step. When pulling a tire from stock, check the air pressure against the desired value. When tires are to be mounted as duals, make sure that the two tires are actually the same size.Measure the outside diameter of every tire after it is mounted and inflated and before it goes into stock. The diameter should be written on the tread so that it is visible when the tire is in the spares rack. Then by simply looking at the treads of the spares in stock, a replacement tire of the correct diameter to match an already mounted dual can be selected. There are many ways of measuring the size of a tire, but two ways appear to be more satisfactory than the others.Both involve measuring the complete circumference of the tire.

The first uses a 14-foot endless steel mating tape. This is a steel band that is formed into a hoop. The hoop is slipped over the tire, pulled up tight, and a reading made. The second type is a pocket-size steel tape. With this it is necessary to hook the end in the tread and roll the tire one revolution, which brings the tape end back around and permits a reading of the circumference.Another way of measuring tires uses calipers that measure tire diameter.The tape method is preferred because it provides an average diameter rather than any one particular diameter measurement.

Mismatched duals have the same effect on the life of tires as low inflation or overload. An underinflated tire on a dual assembly shifts its share of the load to its mate, which then becomes overloaded and frequently fails prematurely. A difference of 15 psi inflation may result in the lesser inflated tire supporting 500 pounds less than the tire with the proper inflation. A similar action occurs when one tire’s diameter is smaller than its mate. A difference of 1/4 inch in diameter may result in the larger tire carrying 600 pounds more than the smaller.

The shift in load becomes more prevalent as the difference in diameters or inflation becomes greater. Improperly matched duals are subject to rapid treadwear because the larger tire carries more load and will wear fast .Although the mismatched duals have different diameters, they must rotate at the same speed. The smaller tire then also wears unevenly because it is forced to scuff over the road. The overall result is abnormal and unequal treadwear for both tires. Improperly matched duals may also lead to sudden air loss as a result of one tire being required to flex severely in doing more than its share of the work.

Always install a new radial tube and a new radial flap in a new tire. Use only tubes designated for radials and make sure the proper size tube and flap is used. Never use undersized tubes. Certain precautions must be taken when mounting used flaps, or damage to the tire and tube will result. New truck and bus flaps can be used with any one of several different tire and rim sizes as recommended. But, once used, the flap must be remounted in the same size tire and on the same size rim from which it was removed. Always use a flap of adequate width to prevent tube pinching.

As a precaution against flap failure,mark the tire and rim size on the flap at the time of removal (if inspection shows that it is not damaged and can be used again). When the flap is again mounted,this marking protects against the danger of misusing the flap with the wrong size tire and rim.

The valve core provides a temporary air seal while air pressure checks are being made, but it will leak air slowly if the cap is loose, missing, or damaged.Use a sealing-type valve cap. A metal cap is preferred but a sealing-type nylon cap is acceptable.

In the case of used tires and tubes,recondition the valve stem every time a tire is mounted. Recondition the threads on both the inside and the outside of the stem with a valve stem rethreader tool. Install only new valve cores. Used or dirty valve cores may be defective.Don’t take a chance. Valve cores must be stocked in clean closed containers at all times, since a small particle of dirt will render a core ineffective.

Use of tire chains may be prohibited according to location. Check the local laws before installing tire chains. When installing tire chains, make sure they are the proper size for the tires on your vehicle and are installed according to the chain manufacturer’s suggestions. Use only SAE class ‘‘S’’ chains.

Other types may damage your vehicle. Use chain tensioners when recommended by the tire chain manufacturer to ensure a tight fit. Loose end links of the tire chain must be secured or removed to prevent the possibility of whipping action damage to the fenders or undercarriage. If possible, avoid fully loading your vehicle when using tire chains.In addition, drive at a reduced speed. Otherwise, your vehicle may be damaged and/or vehicle handling and performance may be adversely affected. Never install tire chains on a TEMPORARY USE ONLY spare tire.

Tire chains must be installed only on the rear wheels and not on the front wheels. Do not use tire chains on dry roads. Driving with chains in such conditions can cause damage to the various mechanisms of the vehicle due to some overstress. When driving on clear paved roads, be sure to change to 2WD.