Choosing the correct tractor tire size is essential for safety, traction, and performance. Whether you’re replacing old tires or upgrading for field conditions, this tractor tire size guide will help you understand what the numbers mean, how to measure properly, and which tires are right for your setup.
Why Getting the Right Tire Size Is Important
Tire size impacts everything from pulling power to fuel efficiency. A wrong tire size can damage the drivetrain, cause tire wear, reduce stability, and increase fuel use. In 4WD systems, mismatched tire sizes between the front and rear axles can lead to gear binding and expensive repairs.
Before replacing any tire, it’s smart to use a
4×4 Tractor Tire Ratio Calculator or
4WD Wheel Ratio Calculator to verify correct rolling ratios.
How to Read Tractor Tire Sizes
There are two common formats: imperial and metric. Both tell you the width, sidewall ratio, and rim diameter.
Imperial Format (e.g., 16.9-30 or 16.9R30)
- 16.9 – Width in inches
- R or – – Radial or bias construction
- 30 – Rim diameter in inches
Metric Format (e.g., 420/85R30)
- 420 – Width in millimeters
- 85 – Aspect ratio (sidewall height is 85% of width)
- R – Radial construction
- 30 – Rim diameter in inches
If you need to convert between formats, use the
Tire Ratio Calculator to find your matching size.
Common Tractor Tire Sizes Chart
This chart lists popular tire sizes and what they’re commonly used for.
| Imperial Size | Metric Equivalent | Approx. Height | Use Case |
|---|---|---|---|
| 6.00-16 | – | 28″ | 2WD Front |
| 11.2-24 | 280/85R24 | 43″ | Rear for compact tractors |
| 12.4-28 | 320/85R28 | 47″ | Utility tractor rear |
| 14.9-28 | 380/85R28 | 52″ | General field use |
| 16.9-30 | 420/85R30 | 57″ | Field tractor rear |
| 18.4-34 | 460/85R34 | 63″ | Row crop tractor |
| 20.8-38 | 520/85R38 | 69″ | High horsepower tractors |
How to Measure Tractor Tires
If you’re not sure what size tire you have, you can measure it manually.
- Width: Measure from sidewall to sidewall (flat, not inflated).
- Height: Measure from ground to top of tread (with full inflation).
- Rim diameter: Measure the inside diameter where the tire mounts.
Always compare your measurements to tire specs before ordering replacements. If in doubt, use the
Wheel Ratio Calculator to check compatibility.
How Tire Size Affects Ballasting
Taller and wider tires may require additional ballast for balance and traction. This is especially true when using loaders or heavy implements.
Use the Ballast Calculator for Tractor Tires to find the ideal weight distribution for your new tire size.
Transporting Your Tractor With New Tires
Bigger tires lift your tractor higher and change the loading angle. To avoid accidents when loading onto trailers, use the
Garden Tractor Ramp Calculator to plan safe ramp height and length.
Tips for Choosing the Right Tractor Tire Size
- Stick to your manufacturer’s recommended sizes when possible
- Check the rim width and tire width compatibility
- Always match rolling circumference in 4WD setups
- Use a ratio calculator before replacing only one axle’s tires
- Ensure your tires are properly inflated before measuring
Conclusion
Choosing the right tractor tire size doesn’t have to be difficult. Once you understand the formats and match your tire specs to the job at hand, you’ll extend the life of your equipment and improve performance in the field.
To make the smartest tire choices, rely on these free tools:
- 4×4 Tire Ratio Calculator
- 4WD Wheel Ratio Calculator
- Ballast Weight Calculator
- Ramp Angle Calculator
- Hourly Rate Calculator
Use this guide as your go-to reference and make confident tire decisions for any tractor, any task.