Combine and Implement Tires: Preparing for Harvest

A combine carries most of its weight on the front axle, and that weight climbs as the grain tank fills. A grain cart is at its heaviest exactly when the field is at its softest. Wagons run loaded from field to bin and back, often on a mix of soil, gravel and pavement, many times a day.

All of that happens in a few weeks, under time pressure, often in conditions nobody chose. It is the worst moment of the year for a tire to fail, and the moment when every tire is working closest to its limit. The agricultural tires page sets out how each machine asks something different of its tires.

The useful window is between the end of one season's work and the start of harvest. The machine is idle, a tire change does not hold anything up, and sizes are easier to get hold of before every farm in the area needs the same ones.

Ag tire sizes are varied, and large or unusual sizes are not always on the shelf. Calling in the weeks before harvest gives the store time to source what you need rather than finding out on the day.

Work through every machine that will run during harvest, not only the combine.

For every tire:

• Read the size off the sidewall exactly as it appears, and write it down. It is the first thing any store will ask for.
• Look for cuts and punctures in the tread and sidewall. Stubble, rock and debris do damage that is easy to miss on a large tire.
• Look for cracking in the sidewall and at the base of the lugs, particularly on machines stored outdoors.
• Look for bulges or separation, which mean the tire should come off.
• Check lug wear. Worn lugs lose traction and flotation exactly when the ground is soft.
• Set the pressure to the figure for the load the machine will carry, using the manufacturer's tables. A combine with a full tank is a different load from an empty one.
• Check the valve stems and caps. A cracked stem is a slow leak waiting for the busiest day.

For the combine:

• Check the drive tires on both sides and compare their wear. Uneven wear between sides can point to a pressure difference or a mechanical issue.
• Check the steer tires at the rear, which are easy to overlook.
• If you run duals, check that the pair on each side match in size and pressure, so one does not carry more than its share.

For the grain cart and wagons:

• Check that each tire is rated for the loaded weight it will carry.
• Look closely at tires that sat outside all year.
• Check wheel bearings and hubs. A failing bearing generates heat that ends a tire quickly.

For the header transport and trailers:

• Read the date codes. These tires often sit for most of the year and age out before they wear out. The RV and trailer tires guide explains how to read the code and what age does to rubber.

Pressure is the setting farmers most often leave alone, and it does a great deal. Too high and the tire has a smaller footprint, more compaction and less traction. Too low and the sidewall flexes beyond what it is built for, which builds heat and shortens the tire's life, especially on road travel between fields.

The right figure depends on the tire, the load and the speed. Use the tire manufacturer's load and inflation tables for the actual weight on each axle, and check pressures cold. Some operations adjust pressure between road travel and field work; if you do, keep the figures written down where the operator can find them.

Not every damaged tire is finished. A cut in the tread of a large ag tire can often be repaired if the damage is in a repairable area and has not reached the casing structure. Damage to the sidewall, separation or a casing that has been run flat usually means replacement.

For large tires, ask about the casing before scrapping it. Six of Purcell's seven retread plants list agricultural casings among what they retread or repair, and the casing is the expensive part of the tire. Retreading explains how the program works and which stores collect casings.

Have this ready when you call:

• The size from the sidewall, for each position that needs a tire.
• The machine by make and model.
• The job: harvest, hauling, road travel between fields.
• The ground: heavy soil, sand, stubble, rock, irrigated.
• How much road travel the machine does.
• What ended the last tire: cuts, wear, sidewall damage, separation.
• When the machine has to be running.

For tracked combines and tractors, see tracks, which are replaced rather than retreaded.

The end of harvest is the start of next year's preparation. Note which tires are near the end of their life while the season is fresh in your mind, and plan replacements over the winter rather than in the rush before the next harvest. The agricultural service page covers how Purcell works with farms through the year, and the irrigation tires guide covers the equipment that sits in the field all season.