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Tyre Identification Markings

For tires using the P-metric designation (e.g., P245/50ZR16)

Format:

[Code][Width]/[Aspect][Speed][Construction][Size]

Code:

P = Passenger
LT = Light truck
T = Temporary
LTP = Light truck, personal use

Width:

Width at widest point, sidewall to sidewall, in millimeters

Aspect Ratio:

Tire height in mm, measured tread to bead, divided by width above, multiplied by one hundred.

Speed ratings:

(The maximum speed the tire can maintain at its maximum load rating)

Q - 100 mph 160kph
R - 106 mph 170kph
S - 112 mph 180kph
T - 118 mph 190kph
U - 124 mph 200kph
H - 130 mph 210kph
V - 149 mph 240kph
W - 168 mph 270kph
Z - more than 168 mph 270kph

Construction:

R - Radial ply
B - Bias belted
D - Diagonal bias

Size:

The diameter of the wheel the tire is designed to be mounted on, in inches.

Other information:

Maximum Air Pressure -
This is the max pressure the tire is designed to hold (note this is more than the recommended inflation pressure)
Maximum Load -
Weight the tire can support
Load Index -
A code that indicates the maximum weight the tire can carry at its speed indicated by its speed rating
Construction -
Tells the number and type of plies used in the construction of the tread and sidewall
DOT Serial Number -
Identifies the plant, manufacturer, and date of production
Tread Wear Index -
A rating of the tire's resistance to wear. 100 is the reference. A 250 rating indicates 2.5 times the wear resistance of the reference tire. This number cannot be accurately translated to mileage.
Traction Index -
A rating of the tire's ability to stop on wet pavement. There are three grades, A, B, and C, with A being the best. This index does not reflect the tire's traction performance on dry, snowy, or icy pavement.
Temperature Index -
A rating of the tire's ability to dissipate and resist heat. There are three grades, A, B, and C, with A being the best.
 

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