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Tire Speed Ratings Explained

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Confused about what that letter means right after your tire size? Ever had a tire shop ask what your speed rating was and didn't know what they meant? Don't know whether you need the more expensive V- or ZR-rated tires that the car came with? Fear not, mighty consumer, for I will edify you.

A tire's speed rating is an indication, expressed as a letter code on the tire sidewall, of a speed the manufacturer expects the tire to be able to sustain over a long period of time without coming apart. This is good information to have for a number of reasons, some of which actually include the likelihood of you ever being able to sustain even the lowest of speeds that passenger car tires are rated for.

The speed rating code is semi-alphabetic and goes like this:

B: 50kph 31mph
C: 60kph 37mph
D: 65 kph 40mph
E: 70 kph 43 mph
F: 80 kph 50mph
G: 90kph 56mph
J: 100kph 62mph
K: 110kph 68mph
L: 120kph 75mph
M: 130kph 81mph
N: 140kph 87mph
P: 150kph 93mph
Q: 160kph 99mph
R: 170kph 106mph
S: 180kph 112mph
T: 190kph 118mph
U: 200kph 124mph
H: 210kph 130mph
V: 240kph 149mph

After V, all ratings begin with ZR and end with either W, Y or (Y) because reasons.

Ok, so there is probably some entirely rational reason for this which completely escapes everyone else in the entire world. Sometimes I want to find the guy who came up with this system and administer a Jethro Gibbs head-slap.

ZRW: 270kph 168mph
ZRY: 300kph 186mph
ZR(Y): 300+kph 186+mph

Obviously, most of these ratings are for tires that do not go on passenger cars. The lowest speed rating you will probably ever see on a passenger car or truck tire is either S or T, which appear most often on dedicated snow tires. You can see that there is quite a safety cushion built into the system – how long do you think you're going to sustain 112 miles per hour on snow tires? How many times do you think you might even reach 112 miles per hour on snow tires?

However, there is another use for this information – it gives you an idea of how well the tires are built for speed. In general, speed ratings of V or above mean that the tire has extra cap plies or even multiple steel belts to provide extra stability at very high speeds – it's built better to perform better. If you're looking for a tire to run on the Autobahn in your M3, you probably want something in the ZR range. Likewise, if you're looking to put inexpensive shoes on a minivan, you probably don't need V-rated tires, even if the manufacturer put them on as the OEM choice.

It's hard to understate how important knowing what the speed ratings really mean can be. If, for example, the manufacturer did put V-rated tires on that minivan, it can be difficult to convince many tire places to put an H-rated on as a replacement. This is less about selling more expensive tires, although that ends up being the functional consequence, and more about fears of liability. The “official line” that tire sellers generally get is “Don't ever put on a lower speed rating than what was already on the car.”

I feel that this, while good advice in general, has to be balanced against what I see as the car manufacturers' predilection for putting increasingly over-rated tires onto new cars. This is something that you as a consumer should be aware of – do you need the more expensive, better built tire that will perform beautifully at 90 mph, or will you be better off with the cheaper one that works just fine at 65-75 mph, but maybe doesn't do as well at 90-100, and might fail at 150? That's ultimately a choice about you, not the tire seller.

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