Speed rating
The speed rating is part of the tire identification. It specifies the speed range for which the tire is approved.
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 ...
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. ...