BMW 318/325/M3/525/535/M5 1989-1993 Repair Information

Tires and Wheels

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TIRE ROTATION



BMW does not recommend rotating the tires. Due to the design of the suspension, the front tires tend to wear on the outside edge and the rear tires wear on the inside edge. When the tires are rotated front to back, the ground contact patch is reversed, resulting in less contact patch area. This can adversely affect the handling, road holding and braking performance of the vehicle.

There is not much to be gained in terms of tire life by rotation, but if you wish to rotate the tires, do so every 3000 miles (5000 km) at maximum. If the period of time between rotations is extended, greater adverse effects in terms of handling, road holding and braking performance of the vehicle can be expected.

Rotation must be accomplished by keeping the tires in the same rotation orientation. This means the tires must be kept on the same side of the vehicle. If the spare is to be included in the rotation, do so from the start as to keep the wear on the spare relative to that of the other tires.

TIRE DESIGN



As every vehicle covered in this guide came stock with radial design tires and bias ply tires are all but a memory, a simple reminder that bias ply and radial tires should never be used together should suffice. The BMW car was designed to use radial tires and the use of bias ply tires would adversely affect the handling, road holding and braking ability of the vehicle.

There is a wide range of tires available for your car ranging from all-season mud and snow tread tires, to high performance spirited driving oriented tires. New tire technology has advanced to where everyday street tires can offer as much performance as yesterdays racing tires, while offering wet weather grip, a comfortable ride and a long tread life. Discussions with your tire retailer can put you on the right track as to the type of tire to buy that will match your needs.

When buying new tires, stick to the stock size tire as recommended by BMW. If the tire size is changed, the performance of the vehicle can be compromised along with affecting the ABS braking system. Maintain the same size tires on all corners of the car. With different sized tires on the car, varying wheel speeds, due to the differing tire circumferences, will confuse the ABS controller and affect its performance. If you desire to change the wheels or tire size, check with your dealer for recommendations, practical value and legal considerations.

When purchasing new tires, buy tires of the same or higher speed rating as the original equipment tires. If the tires are replaced with lower speed rated tires, the vehicle dynamics could be effected. The argument that you don't travel as fast as the tire is rated is not a valid one. There is more to speed rating than what speed you travel. Speed ratings involve the tires ability to dissipate heat and thus the way the tire is constructed. These factors control the behavior of the tire and vehicle.

TIRE STORAGE



Mark the tires with the location on the car from which they came off. This will keep the rotations correct when they are replaced on the car. Store the tires at the proper inflation pressure if they are mounted on wheels. Keep them in a cool dry place, laid on their sides. 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.

TIRE INFLATION



See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: Checking the tread depth with an inexpensive gauge



Click image to see an enlarged view

Fig. Fig. 2: Treadwear indicators show when the tire is worn to its serviceable limit

For the best performance from your tires, check the inflation pressure at least every 2 weeks. It is better to check every week. If the tire pressure is incorrect, driving performance, braking and handling will be affected. Keep an accurate pressure gauge in your glove compartment.

Be sure to check the pressure when the tires are cold as a warm tire will give false readings. As the tire temperature goes up, so does the pressure. For every 18°F (10°C) the pressure is raised 1.5 psi (0.1 bar).

Match your tire pressure to your planned load. Increase the pressure to counteract a heavy load. Follow the guide provided by BMW in the owners manual and on a sticker located on the vehicle itself.

CARE OF WHEELS



Most BMW vehicles are equipped with alloy wheels. Care must be taken when cleaning the wheels. Use only a product formulated for cleaning alloy wheels. Do not use a product containing abrasives, strong acids or alkalis. Do not use water heated to more than 140°F (60°C). Follow the instructions provided with the cleaning product.

Use brushes designed to be used on alloy wheels. These brushes have soft bristles that will not scratch the surface of the wheel. If the wheel is very dirty, allow the cleaning solution to work into the dirt, scrub with the brush and hose off the dirt.

Do not use brake dust shields mounted between the wheel and hub. These shields can block the flow of brake cooling air and cause overheating of the rotor. Differences in materials can cause the lug bolts to loosen when the expansion and contraction rates of the materials vary. To prevent build-up of brake dust on the wheels, wash the wheels often.

Wash the wheels frequently to prevent road dirt, salt and brake dust from corroding the wheels. If contaminants are allowed to sit on the wheel and bake into it with the heat from the brakes, the wheel can become stained. Wash the wheels often to prevent this.

CHANGING TIRES



  1. With the car still on the ground, set the parking brake and put the car in PARK or 1st gear.
  2.  
  3. Place the supplied chock under the rear wheel on the opposite side of the vehicle.
  4.  
  5. On vehicles with the cross spoke type wheels, remove the lug cover with the supplied wrench. Turn the wrench counterclockwise to remove.
  6.  
  7. Loosen the lug bolts. Place the jack in the jacking point. Make sure the ground underneath the jack is stable enough to support the weight of the vehicle. Place a board under the jack on soft ground.
  8.  
  9. Raise the vehicle enough to provide space to fit the spare.
  10.  


CAUTION
Do not go under the car while it is supported solely by the tire changing jack. The jack can slip and fall causing personal injury or death.

  1. Remove the lug bolts and remove the tire. A tire that has been run on while flat can be hot.
  2.  

To install:
  1. Place the centering pin in one of the bolt holes. Place the wheel on the hub over the centering pin. Replace the lug bolts, removing the centering pin after at least one lug bolt is in place. Snug the bolts.
  2.  
  3. Lower the car and torque the lug bolts to 81 ft. lbs. (110 Nm). Replace the lug cover on cross spoke wheels.
  4.  

 
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