What is Load Index & Speed Rating for Tyres?

What is Load Index & Speed Rating for Tyres?

Load index and speed rating of a tyre are mentioned on the sidewall of the tyre. It is important you know exactly what they are so that you can drive safely. Let’s learn more about them.

 

What is Load Index?

The Load Index of a tyre is a numerical code written on each tyre. It denotes the maximum weight that each tyre of your vehicle can carry at the maximum speed given by the manufacturer. It is generally a two- or three-digit number which represents the load-bearing limit of each tyre.

 

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How is Load Index Denoted?

Suppose you see 99W written on the tyre.

In this, the first two digits 99 represent the tyre’s load index and the letter W denotes the speed rating of the tyre. Since 99 is the load index, it means that it can carry a weight of 775 kilograms.

It is mandatory for the load index to be mentioned on all tyres manufactured since 1991, except for Z-tyres. The load index rating can be found mentioned on the sidewall of your tyre between the diameter reading and the speed rating.

 

More About Load Index

You must buy all the tyres of the same load capacity to distribute equal weight on all four tyres of your vehicle. You can even refer to the vehicle owner’s manual to determine the load index of your tyres. Typically, the load indexes of the tyres of passenger cars and light trucks range from 70 to 110.

 

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Load Index Table

Load Index Load in Kg per Tyre Load Index Load in Kg per Tyre Load Index Load in Kg per Tyre Load Index Load in Kg per Tyre Load Index Load in Kg per Tyre Load Index Load in Kg per Tyre
50 190 70 335 90 600 110 1060 130 1900 150 3350
51 195 71 345 91 615 111 1090 131 1950 151 3450
52 200 72 355 92 630 112 1120 132 2000 152 3550
53 206 73 365 93 650 113 1150 133 2060 153 3650
54 212 74 375 94 670 114 1180 134 2120 154 3750
55 218 75 387 95 690 115 1215 135 2180 155 3875
56 224 76 400 96 710 116 1250 136 2240 156 4000
57 230 77 412 97 730 117 1285 137 2300 157 4125
58 236 78 425 98 750 118 1320 138 2360 158 4250
59 243 79 437 99 775 119 1360 139 2430 159 4375
60 250 80 450 100 800 120 1400 140 2500 160 4500
61 257 81 462 101 825 121 1450 141 2575 161 4625
62 265 82 475 102 850 122 1500 142 2650 162 4750
63 272 83 487 103 875 123 1550 143 2725 163 4875
64 280 84 500 104 900 124 1600 144 2800 164 5000
65 290 85 515 105 925 125 1650 145 2900 165 5150
66 300 86 530 106 950 126 1700 146 3000 166 5300
67 307 87 545 107 975 127 1750 147 3075 167 5450
68 315 88 560 108 1000 128 1800 148 3150 168 5600
69 325 89 580 109 1030 129 1850 149 3250 169 5800

 

Speed Rating of a Tyre

The speed rating of a tyre indicates the maximum speed at which the tyre can be driven safely under its approved load capacity. You must use tyres with the right speed rating without which you would be putting lives at risk.

At high speeds, the wheels turn faster which generates more heat. If you do not use tyres that can cope with the extra heat, the tyres may get damaged, or worse, burst.

Speed Rating KM/Hour
L 120
M 130
N 140
P 150
Q 160
S 180
T 190
U 200
H 210
V 240
W 270
Y 300
Z 240+

 

The load index and speed rating together make the service description of the tyre. It is recommended that you know the service description of your tyres whenever you replace the original equipment tyres. You must match or improve the speed rating and load index of your factory tyres even if you don’t plan on pushing the limits. This will help keep your vehicle’s performance consistent.

 

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Z-speed Tires

We saw earlier that except for Z-tyres, all other tyres must have a load index and speed rating mentioned on the tyres. So, what are these Z-tyres?

Z-tyres represent the tyre speed rating with speeds that exceed 240 kmph. These are usually found on exotic sports cars.

After the Z-tyres were created, even higher speed rating tyres were manufactured with speed ratings of W, Y and (Y). W denotes the speed of 270 kmph, Y is 300 kmph and (Y) is more than 300 kmph.

 

How to Find Load Index and Speed Rating

If you are unable to read the service description on the sidewall of the tyre, just look at the owner’s manual. It will have the tyre load index and tyre speed rating mentioned in it. You can even ask a tyre professional for help.

 

Few Important Things to Know

  1. If your tyres carry more weight than its load index, there will be additional stress on your tyres and other vehicle components. It may also lead to increased fuel consumption, poor vehicle handling and even cause tyre failure like cracking or blowout.
  2. You can use tyres with a higher load index than that recommended by the manufacturer, but do not use a tyre with a lower load index. A tyre with a lower load index cannot support the weight of the vehicle and its load.
  3. The same applies when it comes to fitting a tyre with a lower or higher speed. You can fit new tyres with a higher speed rating than the existing tyres but never fit tyres with a lower speed rating.

 

Make sure you carefully check the service description whenever you change the tyres for a safer ride.

 

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