How to Read a Tire Size Code
A size like 225/65R17 gives the tire width in millimeters, sidewall height as a percent of that width, the construction and the rim size in inches.
By Damien VolkmanContributing writer.
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The short answer
The size code on a tire's sidewall describes its shape. Take 225/65R17, the most common full size code among the tires on Wiki Shopping:
| Part | Meaning |
|---|---|
| 225 | Section width: the tire is about 225 millimeters wide |
| 65 | Aspect ratio: the sidewall height is 65% of the width |
| R | Radial construction |
| 17 | Fits a wheel with a 17-inch rim diameter |
Michelin's guide to reading a tire explains the same four parts, and notes that car tires follow the same format as its motorcycle example.
Working out the sidewall height
The aspect ratio is a percentage of the width, not a length. For 225/65R17, the sidewall is about 65% of 225 millimeters, or roughly 146 millimeters. Two tires with the same rim size can have very different sidewalls: a 225/45R17 has a sidewall of about 101 millimeters.
What comes after the size
A tire's sidewall usually shows more after the size, such as a number and a letter (for example 58W in Michelin's motorcycle example). That pair is the service description: the number is the load index and the letter is the speed rating. Michelin's guide explains how to read both. When you replace tires, the size and service description in your vehicle's manual or door label are the ones to match.
Rim sizes on Wiki Shopping
How many of the 2,443 tires on Wiki Shopping list each rim size, on October 23, 2026. Sizes with a filter page link to it.
| Rim size | Tires |
|---|---|
| Up to 14 in | 96 |
| 15 in | 145 |
| 16 in | 252 |
| 17 in | 229 |
| 18 in | 172 |
| 19 in | 61 |
| 20 in | 156 |
| 21 in and up | 161 |
| 22.5 in | 64 |
| 17.5, 19.5 and 24.5 in | 64 |
| Rim size not stated in the listing | 1,043 |
Wiki Shopping reads rim sizes for car and SUV, light truck, commercial truck and trailer tires. The 1,043 tires without one are mostly other kinds: 393 ATV and UTV tires, 257 motorcycle tires and 133 farm and industrial tires, among others. Browse those by vehicle, for example ATV and UTV tires or motorcycle tires.
How to find your size
- Read the sidewall of the tire now on your vehicle, or check the owner's manual.
- Filter by rim size first. It narrows the list fast, for example tires for 17-inch rims.
- Match the full code. Check the width, aspect ratio and service description on the product before you buy. A few full codes already have their own page, such as 225/65R17 tires.
How we count
Each tire on Wiki Shopping has its size read from the store listing. A tire whose listing gives no rim size is counted as "not stated". The counts change as listings are added or removed.
Shop by spec
Tires
Bicycle, All Season
- All-Season Performance: Builds on the Grand Prix 5000 S TR with added puncture protection and grip, so one tire can handle wet, cold and dry roads all year.
- Vectran Breaker and Reinforced Sidewalls: A cut-resistant Vectran Breaker sits under a thicker tread, and reinforced construction improves sidewall protection on rough roads.
- BlackChili Compound: Tuned for grip in all-weather conditions with low rolling resistance. A Lazer Grip micro profile on the shoulders adds control in corners.
- Active Comfort Technology: Vibration damping built into the casing, 2 layers of 110 TPI (220 TPI), smooths rough pavement, with cream sidewalls for a classic look. Handmade in Germany.
- Tubeless Ready, Hookless Compatible: Run with sealant or an inner tube. Size 700x28 (ETRTO 28-622), up to 73 PSI on hookless rims, 15-23mm internal rim width.
Bicycle
- The industry standard in performance training bike tires is back and better than ever, with a refreshed design and increased performance
- The subtle center grooves and shoulder texture in this road tire retain the secure feel of the Zaffiro tires of the past while streamlining the look and feel for the future
- The alternating slick profile and Graphene compound mimic the feel of the Zaffiro’s higher-end siblings while adding durability, at a more approachable price point
- The new casing provides high puncture protection and extended mileage, making the Zaffiro Pro bike tire an unbeatable package for everyday use and for training
- Vittoria is the official tire of USA Cycling. Tire choice of professional riders in the peloton. Winner of Tour de France, Giro d’Italia, Vuelta a España, Classics, World Championships, European Championships and Olympic Games.
Car and SUV, All Season, 18 in
- Tire Only - Wheel Not Included
- Treadwear Warranty: 70,000 miles
- Road Hazard Warranty
- Roadside Assistance
- Improved comfort, handling and traction.
Bicycle, All Terrain, Set of 2
- The information below is per-pack only
- Designed to be compatible with a 26" diameter internal rim, with widths ranging from 19mm to 29mm
- 26 x 1.95 inch mountain bike tire for off road riding
- Wide, blocky knobs deliver enhanced traction when navigating through loose or rocky terrain
- Puncture guard provides extra layer of resistance under tread to help prevent flats
- Durable steel bead contruction, with a recommended PSI range of 40 to 65
- How to fix a flat in 7 easy steps:Remove the wheel from the bike: Use your tire levers to pry the tire up and off the rim. Pull out the old tube. Inflate the old tube. Now, you have two choices: patch or get a new tube. Place the tire and tube back onto the wheel. Inflate your tires back to the recommended pressure and get on with your ride.