Checking tread depth / wheel fastening

When the specified inflation pressure is observed carefully and wheel alignment and shock absorber function are faultless, the tires of balanced wheels wear almost evenly across the entire tread.

For uneven wear, see the fault diagnosis in the "Tires" chapter.

Otherwise, no general statement can be made about the service life of particular tire brands, as service life depends on various factors:

• Road surface

• Tire inflation pressure

• Driving style

• Weather conditions

Above all, sporty driving, hard acceleration and heavy braking promote rapid tire wear.

Warning: The courts require that tires may only be worn down to a tread depth of 1.6 mm; the tread grooves must still be at least 1.6 mm deep across the entire tread. However, as a precaution, it is advisable to replace tires already at a minimum tread depth of 2 mm.

When the tread depth approaches the legally permissible minimum tread depth, i.e. when the 1.6 mm high wear indicators, which are arranged several times around the tire circumference, no longer have any tread, the tires must be replaced. The wear indicators are distributed over the entire circumference of the tire. Their position is marked by the lettering "TWI" and " " on the sidewall.

TWI = Tread Wear Indicator.

Warning: M+S tires (winter tires) only provide adequate grip on mud and snow if their tread is still at least 4 mm deep.

Warning: Inspect the tires for cuts and use a small screwdriver to determine the depth of the cuts.

Therefore: replace tires with deep cuts in the tread for safety reasons.

• Tighten all wheel bolts crosswise to 90 N·m. Do not oil or grease wheel bolts.