How to Read Tire Size - Step-by-Step Guide to Understanding Tire Codes
Reading tire size codes is an essential skill for every vehicle owner. This comprehensive guide will teach you how to decode tire numbers, understand tire measurements, and interpret tire specifications step by step.
Learning to read tire size codes empowers you to make informed decisions about tire selection and maintenance.
Where to Find Tire Size Information
Tire size information is located on the tire's sidewall, typically in a prominent position. The tire size code is a standardized format that provides all the essential information about the tire's dimensions and capabilities.
Tire Size Code Location
205/65R16 95H
This code appears on the tire sidewall and contains all necessary information
Step-by-Step Guide to Reading Tire Size
Step 1: Locate the Tire Size Code
What to Look For:
- Look on the tire sidewall
- Find the largest, most prominent numbers
- Look for format like: 205/65R16 95H
- May be preceded by "P" (passenger) or "LT" (light truck)
Tip: The tire size code is usually the largest text on the sidewall and follows a consistent format.
Step 2: Read the Section Width (First Number)
How to Read:
- First number in the code (e.g., 205)
- Represents width in millimeters
- Convert to inches: divide by 25.4
- Example: 205 mm = 8.07 inches
Example: In 205/65R16, the section width is 205 mm (8.07 inches)
Step 3: Read the Aspect Ratio (Second Number)
How to Read:
- Second number after the slash (e.g., 65)
- Represents sidewall height as percentage of width
- Calculate sidewall height: width × (ratio ÷ 100)
- Example: 205 × (65 ÷ 100) = 133.25 mm
Example: In 205/65R16, the aspect ratio is 65%
Step 4: Read the Construction Type (Letter)
How to Read:
- Letter after aspect ratio (e.g., R)
- R = Radial construction (most common)
- D = Diagonal/Bias ply (older style)
- B = Belted bias construction
Example: In 205/65R16, R means radial construction
Step 5: Read the Rim Diameter (Third Number)
How to Read:
- Number after construction letter (e.g., 16)
- Represents rim diameter in inches
- Must match your wheel size exactly
- Common sizes: 14, 15, 16, 17, 18, 19, 20, 21, 22
Example: In 205/65R16, the rim diameter is 16 inches
Step 6: Read the Load Rating (Fourth Number)
How to Read:
- Number after rim diameter (e.g., 95)
- Represents maximum load capacity
- Scale: 60-150 (higher = more capacity)
- Example: 95 = 1,521 lbs per tire
Example: In 205/65R16 95H, the load rating is 95
Step 7: Read the Speed Rating (Last Letter)
How to Read:
- Letter after load rating (e.g., H)
- Represents maximum safe speed
- Scale: L-Z (higher letters = higher speeds)
- Example: H = 130 mph maximum
Example: In 205/65R16 95H, the speed rating is H
Complete Example: Reading 205/65R16 95H
205/65R16 95H
Let's break down each component
205
Section Width
205 mm = 8.07 inches
65
Aspect Ratio
65% of width
R
Construction
Radial
16
Rim Diameter
16 inches
95
Load Rating
1,521 lbs per tire
H
Speed Rating
130 mph maximum
Additional Information on Tire Sidewall
Other Important Codes
- DOT Code: Department of Transportation certification
- Manufacturer: Brand name and model
- Date Code: Manufacturing date (YYWW format)
- UTQG Rating: Uniform Tire Quality Grade
- Max Pressure: Maximum inflation pressure
- Max Load: Maximum load capacity
Tire Type Indicators
- P: Passenger car tire
- LT: Light truck tire
- T: Temporary spare tire
- ST: Special trailer tire
- No Prefix: European metric tire
- M+S: Mud and snow rated
Common Mistakes When Reading Tire Size
❌ Confusing Width with Diameter
The first number is width in millimeters, not the overall tire diameter. The overall diameter is calculated from all components.
❌ Ignoring Load and Speed Ratings
These ratings are crucial for safety. Never exceed the load or speed ratings specified on your tires.
❌ Reading Old or Worn Codes
If the tire size code is worn or illegible, replace the tire. Never guess at tire specifications.
✅ Best Practices
Always read all components of the tire size code, verify with your vehicle's specifications, and consult professionals when in doubt.
Professional Tips for Reading Tire Size
Reading Tips
- •Clean the Sidewall: Wipe away dirt and debris for clear reading
- •Use Good Lighting: Ensure adequate light for accurate reading
- •Read All Components: Don't skip any part of the tire size code
- •Double-Check: Verify readings with vehicle specifications
Safety Considerations
- •Match Specifications: Ensure tires match vehicle requirements
- •Check Age: Verify tire manufacturing date
- •Inspect Condition: Look for damage or excessive wear
- •Professional Verification: Consult experts when uncertain
Ready to Read Your Tire Size?
Use our interactive tire size calculator to analyze your current tires and find compatible alternatives.