Tire Tread; Summer Tires; Winter Tires - Mini COUNTRYMAN Owner's Manual

Conform to Federal Safety Requirements
All passenger car tires must conform to
Federal Safety Requirements in addition to
these grades.◀
Treadwear
The treadwear grade is a comparative rating
based on the wear rate of the tire when tested
under controlled conditions on a specified gov‐
ernment test course. For example, a tire graded
150 would wear one and one-half (1 1/2) times
as well on the government course as a tire
graded 100. The relative performance of tires
depends upon the actual conditions of their
use, however, and may depart significantly
from the norm due to variations in driving hab‐
its, service practices and differences in road
characteristics and climate.
Traction
The traction grades, from highest to lowest, are
AA, A, B, and C.
Those grades represent the tire's ability to stop
on wet pavement as measured under control‐
led conditions on specified government test
surfaces of asphalt and concrete. A tire marked
C may have poor traction performance.
The traction grade assigned to this tire is based
on straight-ahead braking traction tests, and
does not include acceleration, cornering, hy‐
droplaning, or peak traction characteristics.
Temperature
The temperature grades are A, the highest, B,
and C, representing the tire's resistance to the
generation of heat and its ability to dissipate
heat when tested under controlled conditions
on a specified indoor laboratory test wheel.
Sustained high temperature can cause the ma‐
terial of the tire to degenerate and reduce tire
life, and excessive temperature can lead to
sudden tire failure. The grade C corresponds to
a level of performance which all passenger car
tires must meet under the Federal Motor Vehi‐
Online Edition for Part no. 01 40 2 961 110 - II/15
Wheels and tires
cle Safety Standard No. 109. Grades B and A
represent higher levels of performance on the
laboratory test wheel than the minimum re‐
quired by law.
Temperature grade for this tire
The temperature grade for this tire is es‐
tablished for a tire that is properly inflated and
not overloaded. Excessive speed, underinfla‐
tion, or excessive loading, either separately or
in combination, can cause heat buildup and
possible tire failure.◀
RSC – Run-flat tires
The symbol identifying run-flat tires is a circle
with the letters RSC on the sidewall, refer to
page 224.
M+S
Winter and all-season tires.
These have better winter properties than

summer tires.

XL
Designation for specially reinforced tires.

Tire tread

Summer tires
The tread depth should not be less than
0.12 in/3 mm, although European legislation,
for example, requires a minimum tread depth
of only 0.063 in/1.6 mm. At tread depths less
than 0.12 in/3 mm, there is a great danger of
hydroplaning even in low water depths and at
raised speeds.

Winter tires

The suitability of winter tires for winter driving
is reduced noticeably when their tread depth
becomes less than 0.16 in/4 mm.
MOBILITY
221