Porsche 911 Carrera Owner's Manual page 278

Example of Inscription
Inscription on radial tire
A Tire size
Example: P 295/30 ZR 19 100 Y
P - The tire is designed for Passenger vehicle.
–
This information is not included on all tires.
– 295 - Indication of tire width in mm
– 30 - Indication of tire height to tire width ratio in
percent
276
Practical Tips, Emergency Service
ZR - code letter for radial tires for speeds
–
above 150 mph / 240 km/h There are cur-
rently no standards concerning tire strength at
speeds above 150 mph (240 km/h).
– R - Belt type code letter for radial
– 19 - Indication of rim diameter in inches
– 100 - Load capacity coefficient
Y - Speed code letter
–
– XL (Extra Load) - Tire with increased load
rating
B TIN (Tire Identication Number)
Example: DOT xx xx xxxx xxxx
– DOT - The DOT symbol indicates that the
tires comply with the requirements of the US
Department of Transportation and provides
information about:
– first two-digit code means manufacture's
identification mark.
– second two-digit code means tire size.
– third four-digit code means tire type code.