See Figure 1
Check the air pressure in your vehicle's tires every few weeks. Make sure that the tires are cool. Air pressure increases with higher temperature, and will indicate false reading. A decal located on the glove box door or side door frame will tell you the proper tire pressure for the standard equipment tires.
Never exceed the maximum inflation pressure on the side of the tire. Also never mixed tires of different size or construction (Belted vs Bias-ply, or Radial vs Belted etc.).
It pays to buy a tire pressure gauge to keep in your vehicle, since those of service stations are often inaccurate or broken. While you are checking the tire pressure, take a look at the tread. The tread should be wearing evenly across the tire. Excessive wear in the center of the tread indicates over inflation. Excessive wear on the outer edges indicates under inflation. An irregular wear pattern is usually a sign of incorrect front wheel alignment or wheel balance.
A front end that is out of alignment will usually pull to one side when the steering wheel is released. Conditions which relate to front end alignment are associated by tire wear patterns. Tire treads being worn on one side more than the other, or wear on the tread edges may be noticeable. Front wheels which are incorrectly balance, is usually accompanied by high speed vibration.
See Figure 2
Tires installed on the front or rear of any vehicle are subjected to different loads, breaking, or steering functions. Because of these conditions, tires develop uneven wear patterns. Rotating the tires every 6000 miles or so will result in increased thread life. Use the correct pattern for tire rotation. Refer to Tire Rotation Patterns chart.
Most automotive experts are in agreement that radial tires are better all around performers, giving prolonged wear and better handling. An added benefit which you should consider when purchasing tires is that radials have less rolling resistance and can give up to a 10% increase in fuel economy over a bias-ply tire.
It is recommended that you have the tires rotated and the balance checked every 6000 miles. 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. Some truck, foul-weather and high-performance tires have directional tread, indicated by arrows on the sidewalls; the arrow shows the direction of rotation. They will wear very rapidly if reversed.
Mark the wheel position or direction of rotation on direction tires before removing them.
If your van is equipped with tires having 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 (the tires with the lower rating will wear faster, and could become overloaded), and upset the handling of the van.
When installing the wheels on the vehicle, tighten the lug nuts in a criss-cross pattern.
The tires on your van 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.
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 1 in. (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.
See Figure 3
For maximum satisfaction, tires should be used in sets of five. Mixing or 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. 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.
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.
If they are mounted on wheels, store the tires at proper inflation pressure. 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, a mat or a large stack of newspaper. Keeping them away from direct moisture is of paramount importance. Tires should not be stored upright, but in a flat position.
See Figures 4, 5, 6, 7, 8, 9, 10 and 11
The importance of proper tire inflation cannot be overemphasized. A tire employs air as part of its structure. It is designed around the supporting strength of the air at a specified pressure. For this reason, improper inflation drastically reduces the tires's ability to perform as 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.
Two items should be a permanent fixture in every glove compartment: an accurate tire pressure gauge and a tread depth gauge. Check the tire pressure (including the spare) regularly with a pocket type gauge. Too often, the gauge on the end of the air hose at your corner garage is not accurate 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 generally one that has not been driven for more than three hours.
A plate or sticker is normally provided somewhere in the vehicle (door post, hood or tailgate) which shows the proper pressure for the tires. Never counteract excessive pressure build-up by bleeding off air pressure (letting some air out). This will cause the tire to run hotter and wear quicker.
Once you've maintained the correct tire pressures for several weeks, you'll be familiar with the vehicle's braking and handling personality. Slight adjustments in tire pressures can fine-tune these characteristics, but never change the cold pressure specification by more than 2 psi. A slightly softer tire pressure will give a softer ride but also yield lower fuel mileage. A slightly harder tire will give crisper dry road handling but can cause skidding on wet surfaces. Unless you're fully attuned to the vehicle, stick to the recommended inflation pressures.
All tires made since 1968 have built-in tread wear indicator bars that show up as 1 / 2 in. (13mm) wide smooth bands across the tire when 1 / 16 in. (1.5mm) of tread remains. The appearance of tread wear indicators means that the tires should be replaced. In fact, many states have laws prohibiting the use of tires with less than this amount of tread.
You can check your own tread depth with an inexpensive gauge or by using a Lincoln head penny. Slip the Lincoln penny (with Lincoln's head upside-down) into several tread grooves. If you can see the top of Lincoln's head in 2 adjacent grooves, the tire has less than 1 / 16 in. (1.5mm) tread left and should be replaced. You can measure snow tires in the same manner by using the "tails'' side of the Lincoln penny. If you can see the top of the Lincoln memorial, it's time to replace the snow tire(s).
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 life of the vehicle.
Special wheels are easily damaged and/or scratched. Occasionally check the rims for cracking, impact damage or air leaks. If any of these are found, replace the wheel. But in order to prevent this type of damage and the costly replacement of a special wheel, observe the following precautions: