GM Prizm/Nova 1985-1993 Repair Guide

Tires and Wheels

Print

See Figures 1 through 8

Common sense and good driving habits will afford maximum tire life. Fast starts, sudden stops and hard cornering are hard on tires and will shorten their useful life span. If you start at normal speeds, allow yourself sufficient time to stop, and take corners at a reasonable speed, the life of your tires will increase greatly. Also make sure that you don't overload your vehicle or run with incorrect pressure in the tires. Both of these practices increase tread wear.



Click image to see an enlarged view

Fig. Fig. 1: Tread wear indicators will appear when the tire is worn out



Click image to see an enlarged view

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



Click image to see an enlarged view

Fig. Fig. 3: A penny works as well as anything for checking tread depth; when the top of Lincoln's head is visible, it's time for new tires

Inspect your tires frequently. Be especially careful to watch for bubbles in the tread or side wall, deep cuts, or underinflation. Remove any tires with bubbles. If the cuts are so deep that they penetrate to the cords, discard the tire. Any cut in the sidewall of a radial tire renders it unsafe. Also look for uneven tread wear patterns that indicate that the front end is out of alignment or that the tires are out of balance.

TIRE ROTATION



So that the tires wear more uniformly, it is recommended that the tires be rotated every 7,500 miles. This can only be done when all four tires are of the same size and load rating capacity. Any abnormal wear should be investigated and the cause corrected.

Radial tires may be cross-switched; newer production methods have eliminated the need to keep them on one side of the car. Studded snow tires will lose their studs if their direction of rotation is reversed. Mark the wheel position or direction of rotation on radial studded snow tires before removal.

Avoid overtightening the lug nuts or the brake disc or drum may become permanently distorted. Alloy wheels can be cracked by overtightening. The specified lug nut torque is 76 ft. lbs. for Nova and Prizm cars. Always tighten the nuts in a crisscross pattern.



Click image to see an enlarged view

Fig. Fig. 4: Tire rotation patterns. A is recommended, B is acceptable. Note that the spare tire is not used in the rotation

TIRE DESIGN



When buying new tires, you should keep the following points in mind, especially if you are switching to larger tires or a different profile series.

  1. All four tires should be of the same construction type. Radial, bias, or bias-belted tires should not be mixed. Radial tires are highly recommended for their excellent handling and fuel mileage characteristics. All Novas and Prisms are delivered with radial tires as standard equipment.
  2.  
  3. The wheels must be the correct width for the tire. Tire dealers have charts of tire and wheel compatibility. A mismatch can cause sloppy handling and rapid tread wear. 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. The illustration gives an example of a tire size designation number.
  4.  



Click image to see an enlarged view

Fig. Fig. 5: Common (P-Metric) tire coding. A performance code such as H or V may appear before the R; the designation M+S may appear at the end of the code to indicate a snow or all-season tire



Click image to see an enlarged view

Fig. Fig. 6: Examples of inflation-related tire wear patterns. As little as two pounds under specification can induce premature wear



Click image to see an enlarged view

Fig. Fig. 7: Radial tires have a characteristic sidewall bulge; don't try to measure tire pressure by looking at the tire. Use a quality air gauge



Click image to see an enlarged view

Fig. Fig. 8: Tire size comparison chart

  1. The height (mounted diameter) of the new tires can change speedometer accuracy, engine speed per given road speed, fuel mileage, acceleration, and ground clearance. Tire manufacturers furnish full measurement specifications to their dealers.
  2.  
  3. The spare tire should be usable, at least for low speed operation, with the new tires. Novas and Prizms use a space-saving spare tire mounted on a special wheel. This wheel and tire is for emergency use only. Never try to mount a regular tire on a special spare wheel.
  4.  
  5. There shouldn't be any body interference when the car is loaded, on bumps or in turning through maximum range.
  6.  

TIRE INFLATION



The importance of proper tire inflation cannot be overemphasized. A tire employs air under pressure as part of its structure. It is designed around the supporting strength of air at a specified pressure. For this reason, improper inflation drastically reduces the tire's ability to perform as it was intended. A tire will lose some air in day-to-day use; having to add a few pounds of air periodically is not necessarily a sign of a leaking tire.

Tire pressures should be checked regularly with a reliable pressure gauge. Too often the gauge on the end of the air hose at your corner garage is not accurate enough because it suffers too much abuse. Always check tire pressure when the tires are cold, as pressure increases with temperature. If you must move the vehicle to check the tire inflation, do not drive more than a mile before checking. A cold tire is one that has not been driven for a period of about three hours.

Never exceed the maximum tire pressure embossed on the tire. This maximum pressure is rarely the correct pressure for everyday driving. Consult your owners' manual for the proper tire pressures for your vehicle.

CARE OF SPECIAL WHEELS



If you have invested money in magnesium, aluminum alloy or sport wheels, special precautions should be taken to make sure your investment is not wasted and that your special wheels look good for the lifetime of the car.

Special wheels are easily scratched and/or damaged. Occasionally check the rims for cracking, impact damage or air leaks. If any of these are found, replace the wheel. In order to prevent this type of damage, and the costly replacement of a special wheel, observe the following precautions:



Use extra care not to damage the wheels during removal, installation, balancing, etc.. After removal of the wheels from the car, place them on a mat or other protective surface. If they are to be stored for any length of time, support them on strips of wood. Never store tires upright - the tread will develop flat spots.
 
While driving, watch for sharp obstacles.
 
When washing, use a mild detergent and water. Avoid cleansers with abrasives or the use of hard brushes. There are many cleaners and polishes for special wheels. Use them.
 
If possible, remove your special wheels from the car during the winter months. Salt and sand used for snow removal can severely damage the finish.
 
Make sure that the recommended lug nut torque is never exceeded or the wheel may crack. Never use snow chains on special wheels; severe scratching will occur.
 

 
label.common.footer.alt.autozoneLogo