01

Start with the size: 225/65R17

The largest string on the sidewall tells you the size of the tire. A typical passenger tire might read P225/65R17 102H. Read it left to right and it stops being a code.

P
Passenger tire typeLT, ST, or T replace it for other vehicles.
225
Section width in millimetresMeasured at the widest point of the inflated tire.
65
Aspect ratioSidewall height is 65% of the section width.
R
Radial constructionStandard on almost every modern tire.
17
Rim diameter in inchesHas to match your wheel exactly.
102
Load index850 kg (1,874 lb) per tire.
H
Speed ratingApproved up to 210 km/h (130 mph).
Every part of 225/65R17 102H, decoded left to right.
  • P — Tire type. P means passenger car. LT is light truck, ST is special trailer, and T is a temporary spare. Many metric sizes simply omit the letter.
  • 225 — Section width in millimetres. This is the widest point of the inflated tire, not the width of the tread.
  • 65 — Aspect ratio. The sidewall is 65% as tall as the tire is wide, so 225 × 0.65 = about 146 mm of sidewall.
  • R — Radial construction. Nearly every modern car and light-truck tire is radial.
  • 17 — Rim diameter in inches. It has to match your wheel exactly, with no room for interpretation.
02

Load index and speed rating: 102H

The number and letter after the size are called the service description. The number is the load index and the letter is the speed rating.

  • 102 — Load index. It maps to the maximum load a single tire can carry: index 102 is 850 kg (1,874 lb) per tire.
  • H — Speed rating. A tire rated H is approved for up to 210 km/h (130 mph).

Never fit a tire with a lower load index or speed rating than your vehicle manufacturer specifies. Going higher is generally safe; going lower is not.

  • Common load indexes: 91 = 615 kg, 95 = 690 kg, 98 = 750 kg, 100 = 800 kg, 102 = 850 kg, 105 = 925 kg, 110 = 1,060 kg.
  • Common speed ratings: T = 190 km/h, H = 210 km/h, V = 240 km/h, W = 270 km/h, Y = 300 km/h.
03

The DOT code and the date of manufacture

Look for the letters DOT near the bead area. The last four digits are the tire's birthday: two digits for the week and two for the year.

DOT
Safety certificationMeets U.S. Federal Motor Vehicle Safety Standards.
U2
Plant codeIdentifies the factory that built the tire.
ABC
Manufacturer codeOptional characters for the tire line.
3524
Date of manufacture35th week of 2024.
DOT · plant code · 3524 — built in the 35th week of 2024.
  • DOT — certifies the tire meets the U.S. Federal Motor Vehicle Safety Standards.
  • The characters in between identify the plant and the tire line.
  • The final four digits are the week and year. For example, 3524 means the 35th week of 2024.

On tires built before 2000 the date code had only three digits, so older stock can be ambiguous. Only a four-digit code gives an exact week and year.

04

UTQG: treadwear, traction, and temperature

The Uniform Tire Quality Grading numbers appear on most passenger tires sold in North America. They are useful for comparing tires, not for promising a lifespan.

  • Treadwear — a relative score, not a distance. A 500 tire is rated to last about five times as long as the 100 reference tire under the government test. It is not a warranty.
  • Traction — wet braking grip, graded AA, A, B, or C. AA is the highest.
  • Temperature — heat resistance, graded A, B, or C. A is the highest, and it matters most at sustained highway speeds.
05

Maximum load and cold inflation pressure

You will find wording like “Max load 850 kg (1,874 lb) at 250 kPa (36 psi) cold.” That is the tire's ceiling, not your vehicle's recommendation.

  • Set pressure when the tires are cold, before driving more than a couple of kilometres.
  • Your recommended pressure lives on the driver's door jamb or the fuel-filler placard, not on the tire sidewall.
  • Under-inflation is the most common cause of uneven wear, poor fuel economy, and blowouts. Check monthly and before long trips.
06

Winter markings: M+S and 3PMSF

Two winter marks get confused constantly. They mean very different things.

  • M+S (Mud and Snow) — a manufacturer's declaration that the tread is designed for muddy and snowy conditions. Many all-season tires carry it.
  • 3PMSF — the three-peak mountain snowflake symbol. The tire passed a standardized severe-snow traction test. In Canada, true winter tires are identified by this symbol.
07

Other marks worth knowing

  • Radial / Tubeless — Tubeless means the tire seals against the rim without an inner tube. Tube Type requires one.
  • E-mark — a circled E with a number is European approval. E4, for example, is the Netherlands.
  • CCC, JIS, and INMETRO — regional approval marks from China, Japan, and Brazil.
  • MADE IN — the country of manufacture, paired with the DOT code.
  • Rotation arrow / OUTSIDE — directional tires must spin one way; asymmetric tires must be mounted with the OUTSIDE face facing out.
  • TWI (treadwear indicator) — raised bars inside the grooves show when the tread reaches 1.6 mm (2/32 inch), the legal minimum in most of Canada.

If your vehicle has a tire-pressure monitoring system (TPMS), the valve stem usually holds a sensor. Replacing a wheel can mean a new sensor, which is worth planning before you order.

08

What to send us before you order

You do not need to decode everything yourself. One clear photo of the sidewall, or these numbers, is enough for The Tire Crew to confirm your fitment.

  • The full size code, for example 225/65R17 102H.
  • The DOT date code, so we know the age.
  • How and where you drive — city, highway, winter, all-season, or all-terrain.
  • Whether you want tires only, or tires fitted and balanced on your wheels.