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The meaning of tyre markings

The meaning of tyre markings

Radial, aspect ratio, load index, run flat, TWI… …so many codes on the sidewalls of tyres, but what do they all mean?

For most of us who get a professional to change our tyres, we may never need to know. But just in case you ever want to source your own tyres, or even if you’re just curious, here’s a quick guide to the meaning of tyre markings.

Tyre Size

The tyre size is indicated by a combination of numbers and letters that should look something like this:  195/60 R15 88 H. Each of the numbers and letters in this example refer to the following, but vary from tyre to tyre.

195 = the section width in mm. So this would be 195mm across the tread from sidewall to sidewall.

60 = the aspect ratio, or the profile height of the sidewall as a percentage of the tyre width. In this example, the tyre profile height is 60% of the tyre width.

R = Radial tyre, which counts for most tyres manufactured these days.

15 = the size of the wheel rim in inches.

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Speed rating

The letter refers to the maximum speed at which the tyre can travel. In this case, H means that the tyre can travel at 210kph (130mph). See the table below for the full scale.

Load Index

91 = the tyre’s load capacity. This number is not the weight itself, but represents a point on a scale (615kg in this case).  See the table below for the Load Index scale.

DOT serial number

This is a combination of numbers and letters (e.g. DOT P2XL BCSC 2915) that, first of all, refers to the fact that the tyre meets or exceeds the Department of Transport safety standards (DOT). The following serial number that helps the manufacturer identify the tyre and production facility, and the final four numbers refer to the date on which the tyre was made. This is particularly important when buying second-hand tyres. In this example the tyre would have been produced in the 29th week of 2015.

Reinforced

Some tyres have a higher load index and are often marked with a corresponding symbol, as follows:

Symbol Meaning
XL Extra Load
EXL Extra Load
RF Reinforced
REINF Reinforced
RFD Reinforced

Run Flat Tyres

Run-flat tyres are designed to withstand the pressure of a flat tyre so you can travel a short distance to have the tyre repaired. The code will depend on the manufacturer (ROF, SSR, ZP etc.). Find out more about Membat’s Passion RFT.

Tread Wear Indicator (TWI)

Treat Wear Indicators are raised bumps within the largest treads, distributed evenly around the circumference of the tyre. You can use these indicators to gauge how much wear your tyres have left.

If you’re unsure about any of the markings on your tyres, or about how to select and replace your tyres, always refer to the vehicle manufacturer’s handbook and contact a professional tyre-fitting service.

Speed rating table

Speed Rating Speed (mph) Speed (km/h)
K 68.4 110
L 75 120
M 81 130
N 87 140
P 93 150
Q 99 160
R 106 170
S 112 180
T 118 190
U 124 200
H 130 210
V 149 240
Z 150+ 240+
W 168 270
Y 186 300

 

Load Index Table

Load Index Weight (kg) Load Index Weight (kg) Load Index Weight (kg) Load Index Weight (kg)
61 257 76 500 91 615 106 950
62 265 77 412 92 630 107 975
63 272 78 425 93 650 108 1000
64 280 79 437 94 670 109 1030
65 290 80 450 95 690 110 1060
66 300 81 462 96 710 111 1090
67 307 82 475 97 730 112 1120
68 315 83 487 98 750 113 1150
69 325 84 500 99 775 114 1180
70 335 85 515 100 800 115 1215
71 235 86 530 101 825 116 1250
72 255 87 545 102 850 117 1285
73 365 88 560 103 825 118 1320
74 375 89 580 104 850 119 1360
75 387 90 600 105 875 120 1400