Chrysler Full-Size Trucks 1967-1988 Repair Guide

Tires and Wheels

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See Figures 1, 2, 3 and 4

The tires should be rotated as specified in the Maintenance Intervals Chart. Refer to the accompanying illustrations for the recommended rotation patterns.



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Fig. Fig. 1: Tread can be checked with a penny, if the top of Lincoln's head is visible, it's time for new tires



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Fig. Fig. 2: Tread depth can also be checked with a depth gauge



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Fig. Fig. 3: Wear patterns



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Fig. Fig. 4: Acceptable tire rotation patterns for radial and bias ply tires in 4 or 5 wheel rotations

TIRE ROTATION



See Figure 5

It is recommended that you have the tires rotated and the balance checked every 6,000 miles (9500 km). There is no way to give a tire rotation diagram for every combination of tires and vehicles, but the accompanying diagrams are a general rule to follow. Radial tires can be cross-switched. Truck tires and some high-performance tires sometimes have directional tread, indicated by arrows on the sidewalls; the arrow shows the direction of rotation. They will wear very rapidly if reversed. Studded snow tires will lose their studs if their direction of rotation is reversed.

Mark the wheel position or direction of rotation on directional tires before removing them.

If your truck is equipped with tires that have different load ratings on the front and the rear, the tires should not be rotated front to rear. Rotating these tires could affect tire life (obviously the tires with the lower rating may wear faster, and could become overloaded if they are moved to a position where they must carry a heavier load). Switching tires with different load ratings could also upset the handling of your truck.

When installing the wheels on the vehicle, tighten the lug nuts in a criss-cross pattern. Lug nuts should be torqued to the following figures:



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Fig. Fig. 5: Rim wheel tightening sequence



1967: 65 ft. lbs. (89 Nm)
 
1968-69: 75 ft. lbs. (102 Nm)
 
1970-71: 80 ft. lbs. (109 Nm)
 
1972-74: 65-85 ft. lbs. (89-116 Nm)
 
1975-84: 85-125 ft. lbs. (116-170 Nm)
 
1985-88: 85-110 ft. lbs. (116-150 Nm)
 
1982-88 350 w/Heavy Duty axle (cone nut): 175-225 ft. lbs. (238-306 Nm)
 
1986-88 350 w/Heavy Duty axle (Flanged nut): 300-350 ft. lbs. (408-476 Nm)
 

TIRE USAGE



See Figure 6

The tires on your truck were selected to provide the best all around performance for normal operation when inflated as specified. Oversize tires will not increase the maximum carrying capacity of the vehicle, although they will provide an extra margin of tread life. Be sure to check overall height before using larger size tires which may cause interference with suspension components or wheel-wells. When replacing conventional tire sizes with other tire size designations, be sure to check the manufacturer's recommendations. Interchangeability is not always possible because of differences in load ratings, tire dimensions, wheel-well clearances, and rim size. Also due to differences in handling characteristics, 70 Series and 60 Series tires should be used only in pairs on the same axle; radial tires should be used only in sets of four.



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Fig. Fig. 6: Tire tread wear indicators

Many states have vehicle height restrictions; some states prohibit the lifting of vehicles beyond their design limits.

The wheels must be the correct width for the tire. Tire dealers have charts of tire and rim compatibility. A mismatch can cause sloppy handling and rapid tread wear. The old rule of thumb is that the tread width should match the rim width (inside bead-to-inside bead) within an inch (25mm). For radial tires, the rim width should be 80% or less of the tire (not tread) width.

The height (mounted diameter) of the new tires can greatly change speedometer accuracy, engine speed at a given road speed, fuel mileage, acceleration, and ground clearance. Tire manufacturers furnish full measurement specifications. Speedometer drive gears are available for correction.

Dimensions of tires marked the same size may vary significantly, even among tires from the same manufacturer.

The spare tire should be of the same size, construction and design as the tires on the vehicle. It's not a good idea to carry a spare of a different construction.

TIRE INFLATION



The tires on your truck should have built-in tread wear indicators, which appear as 1 / 2 in. (13mm) bands when the tread depth gets as low as 1 / 16 in. (1.6mm). When the indicators appear in 2 or more adjacent grooves, it's time for new tires.

For optimum tire life, you should keep the tires properly inflated, rotate them often and have the wheel alignment checked periodically. You should check your tire inflation on a monthly basis and always immediately before extended driving. Check your tires when they are COLD (at least three hours after the truck has been stopped and before it has been driven more than one mile or two kilometers). Do not reduce tire pressure when the tires are HOT. And, always use an accurate tire pressure gauge to maintain pressure at the recommended level.

Some late model trucks have the maximum load pressures listed in the VIN plate on the left door frame. In general, pressure of 28-32 psi (193-221 kPa) would be suitable for highway use with moderate loads and passenger truck type tires (load range B, non-flotation) of original equipment size. Pressures should be checked before driving, since pressure can increase as much as 6 psi (41 kPa) due to heat. It is a good idea to have an accurate gauge and to check pressures weekly. Not all gauges on service station air pumps are to be trusted. In general, truck type tires require higher pressures and flotation type tires, lower pressures.

TIRE DESIGN



See Figure 7

For maximum satisfaction, tires should be used in sets of five. Mixing different types (radial, bias-belted, fiberglass belted) should be avoided.

Conventional bias tires are constructed so that the cords run bead-to-bead at an angle. Alternate plies run at an opposite angle. This type of construction gives rigidity to both tread and sidewall.

Bias-belted tires are similar in construction to conventional bias ply tires. Belts run at an angle and also at a 90° angle to the bead, as in the radial tire. Tread life is improved considerably over the conventional bias tire.



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Fig. Fig. 7: Types of tire construction

The radial tire differs in construction, but instead of the carcass plies running at an angle of 90° to each other, they run at an angle of 90° to the bead. This gives the tread a great deal of rigidity and the sidewall a great deal of flexibility and accounts for the characteristic bulge associated with radial tires.

Radial tires are recommended for use on most later model Dodge and Plymouth trucks.


CAUTION
Radial tires must not be used on 1975 and earlier 16.5 x 6.75 wheels! The 1976 and later design wheels can be used with radial tires.

When radial tires are used, tire sizes and wheel diameters should be selected to maintain ground clearance and tire load capacity equivalent to the minimum specified tire. Radial tires should always be used in sets of five, but in an emergency, radial tires can be used with caution on the rear axle only. If this is done, both tires on the rear should be of radial design.


WARNING
Radial tires should never be used on only the front axle!

TIRE STORAGE



All tires should be stored indoors so that there is no danger of water collecting inside them., but keep them away from from sources of heat and ozone such as hot pipes or electric generators. Keep them on their sides in a cool dry place. If the tires are stored in the garage or basement, do not let them stand on a concrete floor. Set them on strips of wood.

Store the tires at the proper inflation pressure if they are mounted on wheels. Be sure the surfaces on which the tires are stored are clean and free from grease, gasoline or other substances which could deteriorate the rubber.

 
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