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Is it time for new tires?

Performance of worn tires will depend on field conditions

Any producer who keeps the same tractor around the farm for several years will eventually need to decide when it’s time to replace the tires. Excessively worn drive tires can seriously affect a tractor’s performance and increase operating costs due to higher fuel consumption, because increased wheel slip caused by poor traction is wasted energy. But at what point, exactly, is a tire on a field tractor due for replacement?

There is no standard rule in determining that, according to James Crouch, farm segment marketing manager at Michelin.

“There are a lot of different things that you can consider here,” he told Grainews. “The first one would obviously be a worn-out tire, if your tread depth is really low. But there’s not really a standard of how low it should be before you change it. It’s almost regional. Your soil type and moisture conditions will influence how effective your tire will be. It’s individually specific.”

“If you’re in a really wet region or year and your tire is really worn out, then your (wheel) slip is going to be really high, and it’s going to waste a lot of fuel. If it’s really dry, you may be able to hold off (replacing them) a little bit longer.”

Many newer-model tractors have wheel slip indicators, making it easy to determine what a tractor’s wheel slip rate is. On an older tractor, however, precisely determining that will be a little harder, and it may come down to using your experience as an operator. Looking at how far dirt is pushed backward by the lugs in a tire track when the tractor is under load can be a useful indicator.

If tire lugs are pushing dirt a long way rearward in a tire track, it can be an indication of excessive wheel slip.

If tire lugs are pushing dirt a long way rearward in a tire track, it can be an indication of excessive wheel slip.
photo: Scott Garvey

“When your slip starts to increase and gets to a point that you know it’s much higher than it used to be, that’s when you need to start looking at changing your tires,” Crouch advises. “Any slip at all is wasted energy. You want to make sure that stays as low as possible and still allows the tractor to do what it is supposed to do.”

“Some of the equipment manufacturers (recommend) from three to seven per cent, three to 10 per cent in some cases,” he continues. “It can be different depending on what your implement is, how much drag it creates. Your machine is designed to work with a little bit of slip. Once you get up to that eight, 10, 12 per cent, you start to waste a little bit of fuel.”

Finding serious damage

Aside from assessing tread wear, finding serious damage is the other factor in deciding when to replace a tire.

“When you start to see cords, it needs to come off,” Crouch says. “Any other damage needs to be looked at on an individual basis. Damage on the shoulder (also) needs to be looked at or repaired. Most of the time if you see enough damage to get your attention, it’s time to call your tire dealer and let them look at it. They can tell you if it can be fixed.”

If it’s time for new shoes on an older machine that still rolls on bias rubber, upgrading to radials could make sense if you expect to continue using the tractor for a few more years. Radials will vastly improve its performance.

“It’ll be night and day different,” says Crouch. “It will change the tractor completely. You’ll never go back to a bias, which is why the market has gone radial so fast. Your initial investment will be much higher, but the longevity will pay for itself two or three times. It will be a complete game changer. ”

“You’re going to be more fuel efficient,” he continues. “The ride quality is so much different on a radial than a bias. If you’re on the road at all, you’re going to see a huge difference in the longevity of the tire, because it’s going to wear evenly as opposed to a bias which is going to wear in the centre because of the construction of the tire.”

And when you replace tires, don’t fall back on internal fluid for ballast, even if the tractor currently uses it.

“We don’t recommend it,” Crouch says. “We would rather see someone put cast iron weights on to get what you need. The reason we do is because when you put fluid into a tire for weight, it changes the entire movement of the tire. Any radial tire is designed to flex. When you put fluid in there, it changes the way the tire is able to move. So it will change the performance of the tire a bit. It will change the contact patch. It will change the way the footprint plays out. It will change the way the tire wears. You lose a lot of the benefit of a radial and you’re starting to backtrack toward a bias.”

About the author

Machinery Editor

Scott Garvey is the machinery editor for Grainews.

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