1942 - 1947 Chevrolet Shop Manual



*10-1*

*Section 10* WHEELS AND TIRES

INFLATION PRESSURES Maintaining the correct inflation pressures is one of the most important elements of tire care. The inflation pressure recommended for any model car or truck is carefully worked out as the best pressure to give an efficient balance of the following factors of good car performance: comfortable ride, stability, steering ease, even tread wear, tire cord life and immunity from blowouts. It is recommended that tires in ordinary use be checked for proper pressure once each week. This will result in added tire life as 2 pounds pressure will normally be lost in a week of ordinary driving. Cars operated at high speeds or in more than ordinarily severe service should have the tires checked at more frequent intervals. Inflation pressures are extremely important in truck tires. The tires should always be inflated so that the full width of the tire tread is in firm contact with the road and that a normal amount of bulge shows on the sidewall of the tire at the bottom. It is extremely detrimental to have the side-walls of the tire bulge too much and it is also detrimental to tire life to have the sidewall bulge too little. The correct bulge for any tire is obtained by loading the tire to the maximum rated load and inflating it with the corresponding inflation pressure shown. Truck tires are expensive and will deliver many more dollars worth of miles if they are properly inflated and proper car taken of all cuts and bruises. TESTING FOR TIRE NOISE The determination of whether tires are causing the noise complained of is relatively simple. The car should be driven at various speeds and note taken of the effect of part throttle, sudden acceleration, and deceleration on the noise condition, as axle and exhaust noises show definite variations under these conditions, while tire noise will remain constant. Tire noise, is, however, most pronounced at speeds of approximately twenty or thirty miles per hour. The tire noise may be further checked by driving the car over smooth pavements or dirt roads (not gravel) with the tires at normal pressure and again over the same stretch of road when the tires have been inflated to fifty pounds pressure. If the noise for which the test is being made is caused by	tires, it will noticeably decrease when the tire pressure is increased, whereas, rear axle noise should show no change in volume as a result of changes in tire pressure. If, on inspection, the tires on the front wheels are found to be creating most of the noise, the alignment of the front wheels should be checked, as excessive tire noise usually results from low tire pressure, incorrect alignment or from uneven tire wear. CORRECTION OF IRREGULAR TIRE WEAR Since irregular tire wear is due to some action which causes certain places on a tire to wear more rapidly than others, the remedy is naturally to correct the condition causing the wear. However, after the adjustments have been made, it is wise to interchange the tires to equalize the future normal wear which will occur. Tires may be alternated several ways to even up irregular wear. However, the following method is the simplest and, in most cases, the most satisfactory. Wheels should be changed without dismounting the tires, right front to spare, spare to right rear, right rear to left front, left front to left rear and the left rear to right front. HEEL AND TOE WEAR Heel and toe wear is a saw-tooth effect with one end of each tread block worn more than the other. The end which wears is
		that which first grips the road when the brakes are applied. High speed driving and excessive use of the brakes will cause this type irregular tire wear, on any type tread design. Heel and toe wear is not so general on the rear tires because of the propelling action creating a counteracting force which

	Fig. 1-Heel and Toe Tire Wear	wears the opposite end
	of the tread blocks. These two stresses on the rear tires cause the tread blocks to wear in opposite directions and