Tire Speed Rating Codes

All vehicle tires are not created equal. Each tire comes with its unique set of specifications which includes the maximum load rating, size, maximum inflation pressure, temperature rating and of course the speed rating. If you are planning to put new wheels on your car, it's essential that you know how to read the tire code specifications that are printed on their sidewalls. In this Buzzle article, I particularly focus on explaining tire speed rating codes.

While shopping for tires, you need to go beyond just looking for the best brands. Just like it's important that you find the best fitting shoes for yourself, it's essential that you find the right wheels for your automobile which can handle the load and survive the driving conditions you subject your vehicle to.

To be a discerning buyer of car tires, you need to learn to decipher tire rating codes to choose the right tire for your car. Your car manual will have information about the correct tire specifications for your car model. Of the dozen or so different specifications that are imprinted on the tire sidewall, one of the most important is the tire speed rating, which will be explained in the following lines.

What is a Tire Speed Rating?

The tire speed rating is indicated by an alphanumeric code, to provide the maximum speed that can be handled by the tire, after which it is bound to suffer major wear and tear. Generally, car tires are so designed, that they can endure their maximum speed rating, for not more than ten minutes, after which they will breakdown.

So the maximum speed value should not be attained or exceeded to maximize tire life. The degree of friction a car tire can handle is dependent on the quality of material it is manufactured from and the degree of load its subjected to. It is essential that you match the maximum speed limit of your car's engine and install car tires which have a speed rating exceeding that limit to ensure long life.

How to Determine the Speed Rating of a Tire?

The ISO Metric sizing system provides an alphanumeric code which is used to determine the speed rating of a car tire. If you read the code off any car tire, it will look something like 'P215/70R16 100V'. In this code specification, speed rating is always specified last, next to the load rating. Here 100 is the load rating of the tire and speed rating is 'V', which indicates a maximum speed of 149 miles per hour. To know what the other symbols mean, refer to this article explaining tire sizes.

Tire Speed Rating Codes Chart

Here is the complete tire speed rating chart, which interprets the alphanumeric code specified on the car tire wall into the maximum speed limit specification in miles per hour and kilometers per hour.

Tire Speed Rating Code	Maximum Speed Limit (mph)	Maximum Speed Limit (km/hr)	Tire Speed Rating Code	Maximum Speed Limit (mph)	Maximum Speed Limit (km/hr)
A1	3	5	L	75	120
A2	6	10	M	81	130
A3	9	15	N	87	140
A4	12	20	P	94	150
A5	16	25	Q	100	160
6	19	30	R	106	170
A7	22	35	S	112	180
A8	25	40	T	118	190
B	31	50	U	124	200
C	37	60	H	130	219
D	40	65	V	149	240
E	43	70	Z	Over 149	Over 240
F	50	80	W	168	270
G	56	90	(W)	Over 168	Over 270
J	62	100	Y	186	300
K	68	110	(Y)	Over 186	Over 300

Hope reading this article wasn't a very 'tiring' experience! Using the tire speed rating code chart presented above, you can determine the maximum speed that a tire can bear before giving in to the forces of friction. If you have a sports car, you will have to opt for tires with a high speed rating bordering in the Z, W or Y zone. However, for city commuting cars and pickups, you can opt for tires with sub-Z speed rating. Refer to your car manual for the exact specifications and buy accordingly.