The sidewall of your tyres is filled with important information that tells you everything you need to know about your tyre.  

The numbers can be a bit overwhelming to the untrained eye, so the best way to understand tire markings is to take an example and break it down, bit by bit. Below are tips and information to help you learn how to read tyre size and other tyre markings.

A tyre size is 185/60R14. 

The 185 represents its section width. 

The number "60" indicates the tyre’s aspect ratio. 

The last number, "14" indicates wheel diameter.

Some off-road tyres use the above type size markings while others still use the older American markings, for example- 31x10.50R15 LT. The significance of these markings is as follows:-

• 31 = the outside diameter of the tyre, in inches.

• 10.50 = the section width of the tyre, in inches.

• R = Radial Construction.

• 15 = Rim diameter in inches.

• LT = Light Truck.

Tyre Section Width

The tyre numbers in the above example tell us that the tyre is 185 millimetres wide. The first number in this series refers to the tyre's section width, or distance from sidewall edge to sidewall edge (in millimetres) when measured up and over the tyre's tread, the larger this number is, the wider the tyre will be.

Aspect Ratio

Aspect Ratio is the ratio of the sidewall height to the section width. The sidewall height of the example tyre above is 60% of its section width. This number can be very indicative of a tyre's purpose. Lower numbers, like 55 or less, mean a short sidewall for improved steering response and better overall handling.

(R) Internal Construction

The "R" refers to radial construction, which has been the industry standard in passenger-car tyres for more than 20 years. Prior to radial tyres, most cars came with bias-ply tyres or X-ply tyres, which had a crude construction that made for poor handling. Bias-ply tyres (which use a "B" for their description) are still used for certain truck applications.

Rim or Wheel Diameter

Wheel Diameter specifies the size, in inches, of the wheel that a tyre fits. The example tyre will only fit a 14-inch wheel

Pay particular attention to this number if you plan on upgrading your wheel size. If your wheel diameter changes, you'll have to purchase a new set of tyres that matches this new diameter.

Other Tyre Markings

(82) Load Index

A tyre's load index is a measurement of how much weight each tyre is designed to support. The larger the number, the higher the load capacity. This is one of the most important numbers on your tyre. To find out what "82" means, it must be looked up on a Load-Carrying Capacity Chart (found in our technical information section) Remember that this is per tyre, which means you have to multiply by four to get the total capacity for a complete set of tyres. If the vehicle has its original tyres, you can just refer to the doorjamb, which lists the maximum cargo capacity with passengers.

Some vehicles are equipped with "XL" tyres. No, it doesn't mean that they're extra large, but it does mean that they are extra-load tyres. The load index on these tyres is much higher than a standard-load tyre — which is why it is important to replace an XL tyre with another XL tyre.

Also, and contrary to popular perception, optional large-diameter wheels with lower-profile tyres tend to have less load-carrying capacity because they contain less air. And it is the volume of air inside the tyre, not the rubber itself or the wheel material that carries the load. 

(H) Speed Rating

The speed rating is a measurement of the speed at which the tyre is designed to run for extended periods. An "H" speed rating signifies that this tyre can be run safely at speeds of up to 210 kph for extended periods. Will it explode if it goes to 220? No, But it might if it is run at that speed for an extended time.

Listed in our technical section is a complete list of the various tyre speed ratings, and their associated letters. The "Z" rating used to be the highest rating for tyres having a maximum speed capability greater than 240 kph, but as tyre technology improved, it is was ultimately split into the "W" and "Y" rating. A "ZR" may sometimes appear in the size designation, as a sort of nod to the prior rating, but it will also be used in conjunction with a W or a Y

DOT Code

The DOT code is used to track tyre production for recall purposes. If a tyre proves to be defective, this number helps keep track of where these tyres ended up so that buyers can be notified of the problem. At the end of the DOT code you'll find a four-digit number. This is the manufacturing date of the tyre. The first two digits stand for the week; the other two are the year. For example, if your tyre had "1610" listed, it was manufactured on the 16th week of 2010.

If you come across a three-digit number, you have a tyre that was manufactured before 2000. A DOT tyre code of "127" indicates the tire was made on the 12th week of the seventh year of the decade. But it's difficult to know whether that was 1997 or even 1987. According to official sources, some tyres produced in the 1990's may have a small triangle following the DOT number to identify the decade. But any tyre that has a three-digit code is history. Tyre experts recommend that tyres that are six or more years old be replaced, regardless of tread depth.

Sometimes the DOT number will be located on the inside of the tyre. In this case, you can either jack up the car to inspect it, or check with your local mechanic or tyre shop. You should also make a habit of checking the manufacturing date on your spare tyre as well.

Maximum Air Pressure

This number refers to the maximum amount of air you can put in a tyre before you harm it, check with a trusted tyre installer for recommended tyre pressure. Remember that all tyre pressure readings are based on cold temperature and NOT whilst tyre is hot.

Traction Rating

A traction rating can also be found on the sidewall of all modern tyres. It can be represented as AA, A, B or C. This is a rating of a tyre's traction when tested for straight-line braking on a wet surface. For this rating, AA signifies the best traction performance and C indicates the worst.

Temperature Rating

The temperature rating refers to the ability of the tyre to withstand heat under high speeds. The ratings, from best to worst, are: A, B and C.

Tread wear Rating

Finally, you might find the word "TREADWEAR" on the sidewall followed by a number like 120 or 180. This is a rating of the tread's durability, as tested against an industry standard. The reference number is 100, so a tyre with a tread wear rating of 200 has an 80 percent longer predicted tread life, while a rating of 80 means a predicted tread life only 80 percent as long as the industry standard.

In addition to all of the above, here is a comprehensive list of other markings you can or may find on your sidewall or appended to the size of the tyre.

• A/T: All-terrain tyre

• C: Commercial; tyres for light trucks. Similar to LT (below)

• EL: Extra Load; tyre for vehicles of heavier standard weights

• H/T: Highway/terrain tyre. For SUVs and 4x4s - less aggressive than full off road tyres - designed for on-road usage.

• LT: Light Truck tyres.

• Made in ...:   Country of production

• M/T: Mud terrain tyre

• OWL: Outline White Lettering

• INSIDE-OUTSIDE: Asymmetric tyres

• SL: Standard Load; tyre for normal usage and loads

• TL: Tubeless

• TT: Tube-type, tyre must be used with an inner-tube

• TWI: Tread Wear Indicator.

• WSW: White Side-Wall

• XL: Extra Load; tyre for vehicles of heavier standard weights. Same as EL

• Arrows: Denotes rotation direction for directional tread.