How to Read a Tire Sidewall Before Winter
Every tire carries a lot of information on its sidewall, but most drivers only glance at the brand name. If you're shopping for winter tires this fall in Cambridge, Kitchener, Waterloo or Guelph, a minute spent reading those markings tells you whether a tire is the right size for your vehicle, whether it's a real winter tire, and how old it is. Here's how to decode it.
Start with the size code
Transport Canada uses this example in its tire safety guide: P 205/55 R16 89 V. Here's what each part means:
P: a passenger tire. You may see LT instead, which means a light truck tire.
205: the width of the tire in millimetres.
55: the aspect ratio, which is the sidewall height as a percentage of the width.
R: radial construction.
16: the wheel diameter in inches.
89: the load index.
V: the speed rating.
Michelin Canada lists a few more prefixes and markings you might see, including C for a commercial van tire, T for a temporary spare, and XL or Reinforced for a tire with a higher load capacity than a standard tire of the same size. It notes that a reinforced tire must be replaced with an equivalent specification.
Load index and speed rating
The number and letter after the size are the tire's service description. Michelin explains that the load index is the maximum load a single tire can carry when properly inflated, and the speed rating is the maximum speed at which the tire can carry that load under specified conditions. Both should meet or exceed what your vehicle manufacturer specifies, and Michelin points out that two tires of the same size can have different load or speed ratings, so check both, not just the size.
You don't have to guess what your vehicle needs. Transport Canada says new tires should be the same size, with the same load capacity and speed rating, as the original tires, and that the size also appears on the tire information label, usually on the driver's door or inside the door frame.
M+S vs the snowflake symbol
This is the marking that matters most for winter. Michelin Canada says M+S (mud and snow) is the manufacturer's own designation and doesn't require standardized winter performance testing. The three-peak mountain snowflake symbol means the tire has met objective testing requirements for winter performance. Transport Canada says tires with that symbol meet specific snow traction requirements and are designed for severe snow conditions. If you want the full story, read our post on the 3-peak mountain snowflake symbol.
How old is the tire? Read the date code
The last four digits of the tire identification number, which follows the letters DOT, are the date code. Under Canada's Motor Vehicle Tire Safety Regulations, the first two digits are the week of manufacture and the last two are the year. Michelin gives the example 4714, meaning the 47th week of 2014. Michelin also notes that age alone doesn't decide whether a tire is still serviceable, and tread wear remains the main indicator. Our guide to winter tire tread depth covers how to check that.
Max pressure is not your tire pressure
Many drivers inflate to the number printed on the sidewall, and that's a mistake. Transport Canada says the maximum pressure on the sidewall is the pressure needed to carry the tire's maximum load, and it's generally not the recommended pressure for your vehicle. Use the pressure on the tire information label or in your owner's manual, and check it when the tires are cold. Transport Canada also notes tires lose about 1 psi for every 5°C drop in temperature, which is one reason a TPMS light often comes on in cold weather.
The maple leaf mark
Transport Canada says the maple leaf symbol is Canada's national tire safety mark. It means the manufacturer certifies that the tire meets Transport Canada requirements, and all new tires sold in Canada must meet the safety standards set under the Motor Vehicle Tire Safety Regulations.
A quick winter tire checklist
Match the size, load index and speed rating on your vehicle's tire information label.
Look for the three-peak mountain snowflake symbol, not just M+S.
Check the four-digit date code so you know how old the tires are.
Inflate to the pressure on your door label, not the max pressure on the sidewall.
Install the same type, size, speed rating and load index on all four wheels, as Transport Canada recommends.
Let SVS Tires & Wheels help
Bring us the size from your sidewall or door label and we'll help you find the right fit. Browse our winter tires or use the Find Tires by Size search. On a budget? Our new economy tires are new tires at prices close to used, and we never sell used tires. Want your winter set on its own wheels? Ask about a wheel and tire package.
When it's time to switch, book a seasonal tire swap. Every install is balanced on Road Force balancing equipment, we service TPMS sensors as part of every tire installation, and your off-season set can stay with us with seasonal tire storage for $80 per season.
Visit SVS Tires & Wheels at Units 7-8, 990 Bishop St N, Cambridge, ON N3H 4V7. We're open Monday to Friday, 10:00 AM to 5:30 PM. Call 519-267-4200 or book online.
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