See also:

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. ...

Removing a wheel
  Unscrew the wheel bolts. Do not place wheel bolts in sand or on a dirty surface. The bolt and wheel hub threads could otherwise be damaged when you screw them in.   Remove the w ...

Purity
Assuring the purity of DEF is particularly important with respect to avoiding malfunctions in the exhaust gas aftertreatment system. If DEF is pumped out of the DEF tank, e.g. during repair wo ...