BMW Z4 ROADSTER Owner's Manual page 272

MOBILITY
ZR tires: reinforced radial tire for speeds ex-
ceeding 150 mph/240 km/h
Maximum tire load
Maximum tire load is the maximum permissi-
ble weight for which the tire is approved.
Locate the maximum tire load on the tire
sidewall and the Gross Axle Weight Rating –
GAWR – on the certification label on the driver
door B-pillar. Divide the tire load by 1.1. It must
be greater than one-half of the vehicle's Gross
Axle Weight Rating – GAWR. Note, front vs.
rear GAWR and tire loads, respectively.
Speed letter
Designation Maximum speed
Q up to 100 mph/160 km/h
R up to 106 mph/170 km/h
S up to 112 mph/180 km/h
T up to 118 mph/190 km/h
H up to 131 mph/210 km/h
V up to 150 mph/240 km/h
W up to 167 mph/270 km/h
Y up to 186 mph/300 km/h
(Y) above 186 mph/300 km/h
Tire Identification Number
DOT Code: DOT xxxx xxx 1923
xxxx: manufacturer code for the tire brand
xxx: tire size and tire design
1923: tire age
Tires with DOT codes meet the guidelines of
the U.S. Department of Transportation.
272
Wheels and tires
Online Edition for Part no. 01405A88B63 - VI/23
Tire age
Recommendation
Regardless of the tire tread depth, replace tires
at least every 6 years.
Manufacture date
You can find the manufacture date of the tire
on the tire sidewall.
Designation Manufacture date
DOT ... 1923 19th week of 2023
Uniform Tire Quality Grading
Quality grades can be found where applicable
on the tire sidewall between tread shoulder
and maximum section width.
E.g.: Treadwear 200; Traction AA; Tempera-
ture A
DOT Quality Grades
Treadwear
Traction AA A B C
Temperature A B C
All passenger vehicle 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. E.g., a tire graded 150
would wear one and one-half, 1 g, 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, how-
ever, and may depart significantly from the
norm due to variations in driving habits, service
practices and differences in road characteris-
tics and climate.
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