See also:

Ruts and gravel roads
Observe the following rules when driving along ruts in off-road terrain or on roads with loose gravel: Check that the ruts are not too deep and that your vehicle has sufficient clearance. O ...

DEF
Important safety notes For BlueTEC vehicles only. DEF is a non-flammable, non-toxic, colorless, odorless and water-soluble fluid. Rinse surfaces that have come into contact with DEF immediately ...

Treadwear indicators
Narrow bars (tread wear bars) that are distributed over the tire tread. If the tire tread is level with the bars, the wear limit of 1/16 in (1.6 mm) has been reached. ...