Should You Change Wheels?
We get quite a few inquiries where tractor owners are considering rear wheel conversions for their particular model. Even though we do not sell tires or wheels, they are inquiring from us as to the best size wheel to achieve a particular ballasted weight ratio. Usually, they just want to add heavier weights to their tractor. Some just want to go faster. Very often, they have not considered the ramifications of failing to maintain the proper rolling circumference group size. This is extremely important for all 4WD, MFWD (Mechanical Front-Wheel Drive) tractors, and ILS (Independent Link Suspension) equipped tractors.
First, before considering wheel/tire conversions, you should make sure your machine is properly ballasted and operating with the correct inflation pressures. Tire/wheel conversions are not always the best solution to a problem. Sometimes it may take a different tractor or it may require your current tractor to be ballasted differently. We recommend that tire/wheel conversions be the last thing you consider to improve your machine’s performance.
The RCI is the distance a tire travels in one revolution. Tires are placed into group designations with similar RCI values.
Each RCI Group has an even progression, where the next group size is 5.4% larger than the previous group, +/- 0.2% tolerance.
It is critical on 4WD, MFWD and most ILS tractors that you maintain the correct front to rear lead/lag relationship by knowing your mechanical ratio and keeping in mind the rolling circumference index (RCI). These tractors are designed around specific ratios required between the RCI of your front and rear tires. Many of you will know these as 5-Step Tractors. This means that the rolling circumference group size between the front tires and the rear tires is 5 group steps apart. Note: there are also many 4 and 6 step tractor models also available.
Using tires/wheels with improper group steps between front and rear tires/wheels can cause serious damage. We urge you to get good advice from your dealer or ag tire professional before making these types of conversions. There is a lot of calculators, charts, and forums spread across the internet that claim to address this issue. Be aware; tire manufacturers may (and often do) have differing tolerances and “close enough” may result in poor performance and expensive repairs.
If you are considering a wheel conversion on your machine, READ THIS, and discuss with a professional.
As always, we invite you to contact us regarding your specific situation and equipment.
This blog is general information only, representing the opinions of the author, and does not cover all aspects of the subject matter. Use of the information contained herein is voluntary.
