Wheel Tire Size Calculator Compare Rims N Tires

This wheel and tire size calculator helps you determine the correct tire size for your vehicle based on rim diameter and tire width. Whether you're upgrading your tires or need to match a specific size, this tool provides accurate measurements and compatibility information.

How to Use This Calculator

Using our wheel tire size calculator is simple. Follow these steps to get accurate measurements:

Enter the rim diameter in inches.
Select the tire width in millimeters.
Choose the aspect ratio (sidewall height as a percentage of width).
Click "Calculate" to see the results.

The calculator will display the overall tire diameter, tire size code, and compatibility information. You can also compare different tire sizes using the chart feature.

Formula Explained

The tire size calculation uses the following formula:

Overall Diameter = (Rim Diameter × 25.4) + (Tire Width × Aspect Ratio)

Tire Size Code = Width/Aspect Ratio × Rim Diameter

Where:

Rim Diameter = Diameter of the wheel rim in inches
Tire Width = Width of the tire in millimeters
Aspect Ratio = Sidewall height as a percentage of width

This formula converts inches to millimeters and calculates the total diameter of the tire including the rim and sidewall.

Worked Example

Example Calculation

Rim Diameter: 17 inches

Tire Width: 225 mm

Aspect Ratio: 50%

Overall Diameter: (17 × 25.4) + (225 × 0.5) = 431.8 + 112.5 = 544.3 mm

Tire Size Code: 225/50R17

This example shows how to calculate the overall diameter and size code for a 225/50R17 tire. The calculator provides these values instantly for any input combination.

Tire Size Comparison

Compare different tire sizes to find the best fit for your vehicle. The table below shows common tire sizes and their characteristics.

Tire Size	Width (mm)	Aspect Ratio	Rim Diameter	Overall Diameter
205/55R16	205	55	16	634.5 mm
225/45R17	225	45	17	648.3 mm
245/40R18	245	40	18	683.8 mm
255/35R19	255	35	19	719.3 mm

This comparison table helps you understand the differences between various tire sizes. The overall diameter is particularly important for vehicle clearance and suspension geometry.

Frequently Asked Questions

What is the difference between tire width and aspect ratio?

Tire width is the measurement across the widest part of the tire, while the aspect ratio is the height of the sidewall as a percentage of the width. Together, these determine the overall diameter of the tire.

How do I know what tire size to buy for my vehicle?

Check your vehicle's owner's manual or the sticker on the driver's side door jamb. The tire size code (e.g., 225/50R17) will be listed there. You can also use our calculator to verify compatibility.

Can I mix different tire sizes on the same vehicle?

It's generally not recommended to mix different tire sizes on the same vehicle. This can affect handling, traction, and even void your warranty. Always use tires that match the manufacturer's specifications.