Winter Tire Buying: What the Codes & Symbols Really Mean
We covered this very topic back in June, so large swaths of information presented in this post will be identical to what was published six months ago. However, with many parts of the country currently dealing with visits from Mother Nature and Old Man Winter, we thought it prescient to circle back and update the idea with a new focus on winter tires.
To start the conversation, note we use the phrase ‘winter tires’ and not ‘snow tires’. This is because modern rubber of this sort begins to pay dividends in terms of traction once the mercury dips below approximately 45 degrees Fahrenheit. There doesn’t always need to be a layer of the white stuff for winter tires to work better than all-seasons.
Look for the three-peak mountain snowflake symbol. This is an industry standard, one earned by tires which pass a specific set of testing criteria, unlike the nebulous ‘M+S’ label which is simply based on tread pattern geometry. High quality winter tires such as the Nokian Hakkapeliitta or Michelin Pilot Alpin will have specialized compounds, tread designs, and build quality to serve up the maximum possible amount of traction when the going gets tough.
[Images: Nitto, RoadX, Nokian, Tricky_Shark/Shutterstock.com]
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The first, and most commonly queried, set of numbers on the sidewall of a tire are its sizing figures. You may know the ones - they look like a jumble of unrelated digits which have been strung together by an AI program. The string of 205/55R16 is a good example of a common tire.
The first three digits (205, as an example) are the width of the tire tread in millimetres. In other words, the higher this value, the wider the measure of a tire. Most widths start with a ‘2’ these days, even affordable cars. One might encounter the scattered secondhand econobox on a used lot which is smaller, but it is uncommon on present day new cars. Similarly, some performance vehicles may have huge tires which start with a ‘3’ - think the rear tires on a Corvette, for example.
The second two digits (55, in our example) refer to the size of the tire’s sidewall. This is the area of rubber between the edge of the metal wheel and the tire’s tread surface. This figure is read as a percentage of the tire width. Here, the sidewall is 55 percent of the 205 mm tread width. This number will be higher on tires fitted to off-road trucks, for example, since a big sidewall is important to try and guard against damage while sporty vehicles may have a low number. Gearheads sometimes refer to this number as a ‘series’; our example could accurately be called a “55-series” tire. Remember, since this is a percentage, it is difficult to directly compare tires of different sizes. A 55-series tire with a 205 mm width would have a much smaller sidewall in terms of actual measure than a 55-series tire with a 305 mm width. It is a number which is in proportion to something else.
Finally, the last two digits (16, as given above) call out the diameter of the metal wheel in inches on which the tire will be used. The digits 17 would be a seventeen-inch tire, and so forth. Alert readers will have now realized each of the three number groups - all of which are important - refer to completely different styles of measure: millimetres, percentage, and inches. Make no wonder workers at tire shops often have headaches.
That’s the main set of digits on a tire which a car owner should know how to read. However, there are some other secondary numbers and characters which can also help a person make smart buying decisions. The age of a tire can typically be determined by looking for a four-digit code, also printed somewhere on the sidewall. Generally circled by an oval to help with identification, these four digits are called the date code and tattle on the week and year a tire was originally manufactured. For example, a date code of 0425 indicates the tire was produced on the fourth week of 2025. When looking at a new vehicle, this information is largely academic since shoppers know the thing rides on four new tires. But in the used car market, it is helpful to know how the age of tires on the machine one is considering to buy. A seller could accurately state that a car’s tires were recently installed but a quick look at the date code might reveal the rubber is a decade old. Maybe the seller is not technically lying - but it still could be deceitful if the buyer is expecting brand new tires based on the statement.
