GM: Electra/Park Avenue/Ninety-Eight 1990-1993

Tires and Wheels

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TIRE INFLATION



The inflation should be checked at least once per month and adjusted if necessary. The tires must be cold (driven less than one mile) or an inaccurate reading will result. Do not forget to check the spare.

Information on tire size, vehicle capacity weight and recommended tire inflation pressure for your vehicle can be found on the Tire Placard (decal) located on the rear of the driver's door. If you cannot find the decal, a local automobile tire dealer can furnish you with information. If the tires are not original equipment, refer to the sidewall of the tire for that manufacturer's specifications.

TIRE INSPECTION



Inspect the tires regularly for wear and damage. Remove stones or other foreign pieces which may be lodged in the tread. If tread wear is excessive or irregular it could be a sign of front end problems, or simply improper inflation.

Inspect tires for uneven wear that might indicate the need for front end alignment or tire rotation. Refer to the diagram for possible causes according to tire wear patterns. Tires should be replaced when a tread wear indicator appears in two or more grooves in three locations or if the tread depth is less than 1 / 16 in. (1.6mm) on any two adjacent tread grooves, or if they violate any code in your state's annual state inspection.

When purchasing new tires, give some thought to these points, especially if you are switching to larger tires or to another profile series:

  1. 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. For radial tires, the rim width should be 80% or less of the tire (not tread) width.
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  3. 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 makers furnish full measurement specifications. Speedometer drive gears are available from gm dealers for correction.
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Dimensions of tires marked the same size may vary significantly, even among tires from the same maker.

  1. The spare tire should be usable, at least for low speed operation, with the new tires.
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  3. There should not be any body interference when loaded, on bumps, or in turning.
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  5. Never mix size, tread type or construction (radial with non-radial) tires on the same axle. It's not really a good idea to mix the above on the car at all, except maybe with snow tires since they are normally temporary. Mixing non-matched tires can lead to all sorts of potentially dangerous handling problems.
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  7. The only sure way to avoid problems with the above points is to stick to tire and wheel sizes available as factory options.
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TIRE ROTATION





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Fig. Fig. 1 Tire rotation pattern

Tire wear can be equalized by switching the position of the tires about every 6000 miles. If possible, including a conventional spare in the rotation pattern can give up to 20% more tire life. If front end problems are suspected, have them corrected before rotating the tires. The following should be considered when rotating tires:

  1. Do not include a `Spacesaver' spare tire in the rotation pattern.
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  3. Tires should be rotated periodically to get the maximum tread life available. A good time to do this is when changing over from regular tires to snow tires, or about once per year. If front end problems are suspected, have them corrected before rotating the tires.
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  5. Mark the wheel position or direction of rotation on radial or studded snow tires before removing them.
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  7. Avoid overtightening the lug nuts to prevent damage to the brake disc or drum. Alloy wheels can also be cracked by overtightening. Use of a torque wrench is highly recommended. Torque the lug nuts in a criss-cross sequence to 100 ft. lbs. (136 Nm).
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TIRE STORAGE





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Fig. Fig. 2 Return the jack and other accessories to their compartment inside the trunk

Store the spare tire and all ACcessories in their proper places in the trunk. Leaving them out invites damage and noise in the trunk area.

Store the tires at proper inflation pressure if they are mounted on wheels. All tires should be kept in a cool, dry place. If they are stored in the garage or basement, do not let them stand on a concrete floor; set them on strips of wood.

CARE FOR ALUMINUM WHEELS



Aluminum wheels should be cleaned and waxed regularly with products developed specifically for aluminum products. Read the label of any product you are considering using prior to application. Do not use abrasive cleaners because they may damage the protective coating.

 
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