What is Tyre Load Index? Understanding Load Index and Speed Rating for Safe Driving

The load index and speed rating of a tyre are crucial factors for safe driving, and they are prominently displayed on the sidewall of each tyre. It’s imperative to understand these codes to ensure the proper functioning and safety of your vehicle. In this guide, we will delve into the significance of load index and speed rating.

 

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.

 

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.

 

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.

 

Know Radial vs Bias Tyres

 

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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