Improve Accuracy, Precision Farming Performance, and Safe Operation with the Bolec ERB205

Modern tractors are frequently fitted with different tyre sizes to improve traction, reduce soil compaction, or adapt to specific farming applications. While changing tyres offers many benefits, it can also affect the vehicle’s speed signal—leading to inaccurate speed readings and reduced performance of electronic control systems.

The Bolec ERB205 Electronic Ratio Box provides a simple and reliable way to correct these speed signal errors without replacing expensive factory electronics.

Why Do Farmers Change Tractor Tyre Sizes?

Changing tyre size is a common upgrade for modern agricultural machinery. Farmers often choose larger or different tyres for several practical reasons.

1. Reduce Soil Compaction

Larger flotation tyres spread the tractor’s weight across a larger footprint, helping to:

• Reduce soil compaction
• Protect crop root systems
• Improve water infiltration
• Increase long-term crop yields

Healthier soil leads to healthier crops.

2. Increase Traction

Larger tyres create a bigger contact patch with the ground, providing:

• Less wheel slip
• Better pulling performance
• Lower fuel consumption
• Increased productivity during cultivation and tillage

3. Improve Ride Comfort

A larger tyre can absorb bumps more effectively, reducing vibration and operator fatigue during long working days.

4. Adapt to Different Farming Operations

Different farming applications require different tyre configurations.

Examples include:

• Row crop tyres
• Flotation tyres
• Dual wheels
• Narrow transport tyres

Each configuration changes the rolling circumference of the tractor.

5. Replace Unavailable or Expensive OEM Tyres

Sometimes the original tyre size is difficult to source or significantly more expensive.

Choosing an alternative size can reduce operating costs while maintaining similar performance.

How Does Tyre Size Affect Tractor Speed?

Most tractors calculate vehicle speed from sensors mounted on the transmission, axle, or wheel.

These sensors may use:

• Hall Effect sensors
• Magnetic pickup sensors
• Transmission pulse generators

When the tyre diameter changes, the tractor travels a different distance with every wheel revolution.

For example:

Original tyre circumference: 5.20 metres

New tyre circumference: 5.50 metres

Although the sensor generates the same number of pulses, the tractor now travels further with each revolution.

The result is an incorrect speed signal.

Why Accurate Speed Matters

An incorrect speed signal affects much more than just the speedometer.

Modern tractors rely on accurate vehicle speed for numerous electronic systems.

Precision Agriculture

Many precision farming systems use vehicle speed to control:

• Auto-steering
• Section control
• Variable-rate application
• GPS guidance

An incorrect speed signal reduces overall system accuracy.

Sprayer Calibration

Sprayers calculate chemical application rates using ground speed.

If speed is incorrect, operators may experience:

• Over-application
• Under-application
• Increased chemical costs
• Reduced crop protection

Seeder and Fertiliser Controllers

Incorrect speed can affect:

• Seeding population
• Fertiliser application
• Plant spacing
• Overall field consistency

Road Transport

When travelling between properties, an inaccurate speedometer can make it difficult to maintain safe road speeds and comply with local regulations.

Safety Matters

Changing tyre size also changes the way a tractor handles.

Larger tyres, flotation tyres, or dual-wheel conversions can alter:

• Ground clearance
• Centre of gravity
• Turning characteristics
• Braking behaviour

Maintaining an accurate speed indication helps operators make informed driving decisions, particularly when:

• Working on slopes
• Transporting heavy implements
• Driving on public roads
• Operating with front-end loaders
• Travelling between paddocks

While the ERB205 is not a rollover prevention device, it helps maintain accurate vehicle speed information after tyre size changes, supporting safer operation and ensuring connected electronic systems receive the correct speed signal.

The Bolec ERB205 Solution

The Bolec ERB205 Electronic Ratio Box is designed to correct frequency-based speed signals by applying a precise correction ratio between the sensor and the receiving instrument or controller.

Instead of replacing sensors or factory ECUs, the ERB205 simply adjusts the signal to match the new tyre size.

Benefits include:

• Accurate speedometer readings
• Correct speed signal for electronic controllers
• Simple DIP-switch adjustment
• No software or programming required
• Reliable operation on both 12V and 24V systems

Key Features

• Compatible with Hall Effect and Magnetic Pickup sensors
• Adjustable ratio from 0.025 to 3.1875
• Fine adjustment in approximately 1.25% increments
• Square wave output with multiple output configurations
• Supports 12V and 24V DC electrical systems
• Compact, durable design suitable for harsh agricultural environments
• Australian designed and manufactured

Typical Agricultural Applications

The ERB205 is ideal for:

• Tractor speedometer correction
• Tyre size conversions
• GPS speed calibration
• Auto-steer systems
• Sprayer controllers
• Fertiliser spreaders
• Seed drills
• Harvesters
• Forestry equipment
• Construction machinery

Frequently Asked Questions

Will changing tractor tyres affect my speedometer?

Yes. A different tyre diameter changes the distance travelled per wheel revolution, which can result in inaccurate speed readings.

Can the ERB205 correct the speed signal?

Yes. The ERB205 adjusts the frequency signal so the receiving gauge or controller displays the correct speed.

Does it work with Hall Effect sensors?

Yes. The ERB205 supports both Hall Effect and Magnetic Pickup input signals.

Is it suitable for 24V tractors?

Absolutely. The ERB205 is compatible with both 12V and 24V electrical systems.

Is the ERB205 a rollover prevention device?

No. The ERB205 is not a safety or rollover prevention system. It is an electronic signal correction module designed to restore accurate speed information after tyre size changes. Accurate speed information can support safer operation and improve the performance of connected electronic systems, but it does not prevent rollovers.

Conclusion

Changing tractor tyre size is one of the best ways to improve traction, reduce soil compaction, and optimise field performance. However, it can also create speed signal errors that affect vehicle instrumentation, precision farming equipment, and electronic controllers.

The Bolec ERB205 Electronic Ratio Box offers a cost-effective, reliable solution by restoring the correct speed signal without replacing factory electronics.

Whether you’re upgrading tyres, fitting flotation wheels, or recalibrating precision agriculture equipment, the ERB205 helps keep your tractor’s electronic systems operating accurately and efficiently.