Irrigation Tires: What Pivot Tires Need

A tractor tire works hard for hours and then rests. A pivot tire does something stranger: it moves very slowly, often for long stretches, over ground the system is soaking as it goes. It carries a steady load from the span and tower above it, and in between runs it can sit still for days in direct sun.

That combination produces a short list of problems that account for most pivot tire trouble.

Wheel tracks. Each tower follows the same circle or line every pass. On wet soil the tires cut a track that deepens over the season. A deep enough track makes the tower work harder, can strain the drive train, and can get a tower stuck, which on many systems stops the whole pivot.

Flats and low pressure. A tire running low sinks deeper, cuts a worse track and flexes its sidewall more than it should. A tire that goes fully flat can leave a tower behind the rest of the span. Many systems are designed to shut down when a tower falls out of line, which protects the structure and costs a day of watering.

Sun and weather damage. Tires that spend the season outdoors, and often the winter too, age from ultraviolet light and weather. Sidewall cracking is common on older pivot tires and is easy to miss from the ground.

Damage from debris and crop residue. Stalks, stones and anything left in the field can cut a tire moving slowly over it, and a slow leak on a remote tower can go unnoticed for a long time.

Walk the system before the first irrigation of the year and look at every tower.

• Pressure. Check each tire against the figure recommended for the tire and the tower weight. Low tires are the most common and most avoidable cause of trouble.
• Sidewalls. Look for cracks, cuts and bulges, especially on the side that faced the sun.
• Tread. Check the lugs for wear and for damage from stalks and stones.
• Valve stems. Cracked or leaking stems are a frequent source of slow leaks.
• Wheels. Look for rust, bent rims and loose or missing lug nuts.
• Drive components. A wheel that is hard to turn puts extra load on the tire. Anything that sounds or feels wrong in the gearbox or drive line is worth having looked at.
• Matching. Tires on the same tower should match in size so the tower tracks straight.

Write down each tower's tire size as you go. When something does fail mid-season, having the size on paper saves a trip out to read it.

Wheel tracks are easier to prevent than to repair. Approaches farms commonly use include:

• Keeping pressures correct. A properly inflated tire rides on top of the soil rather than sinking into it.
• Tire and tread choice. Larger tires spread the load over more ground, and some tread patterns are designed to leave a shallower, less damaging track. Ask the store which designs suit your soil and system.
• Filling and leveling tracks between seasons before they become too deep to cross.
• Track management on the ground itself, such as adjusting the watering pattern near the tower path where the system allows it.

What works depends on the soil, the slope and the system. Heavy soils that stay wet rut differently from sandy ones, so tell the store what your ground is like when you ask about tires.

A small puncture in the tread can often be repaired. Sidewall damage, separation, bulges and heavy cracking usually mean the tire should be replaced. When one tire on a tower is replaced, check whether the other still matches it in size and wear, since an uneven pair can pull the tower off line.

Because a flat tower stops the system, many operations keep at least one spare tire and wheel for their most common size, so a failure becomes a swap rather than a wait.

• The size from the sidewall, exactly as it reads.
• The system type and how many towers.
• The soil type and whether wheel tracks are a problem.
• How many tires you need now, and whether you want a spare.
• What ended the last tires: cracking, cuts, flats or wear.

Irrigation tires are part of the agricultural tires category. Sizes vary by store, so call with the size before you plan a change.

The right time to deal with pivot tires is the same as for the rest of the farm's machinery: between seasons, before anyone needs the system to run. The harvest preparation guide covers the combine, carts and wagons, and the agricultural service page sets out how Purcell works with farms. For tracked equipment on the same operation, see tracks.