Why are combine wheels prone to cracking?

Combine Weight

Let’s deal with the big one first: the combine. A class 9 combine approaches 20 tons per axle when empty. Even a class 7 or class 8 combine is no shrimp and still puts an enormous amount of weight on its axles.

But a combine doesn't stay empty, of course. And we all know how important it is to keep the combine moving, so a good majority of combines have hopper extensions on them. If you've added a hopper extension and haven't beefed up your tire and wheel setup, you could be asking for wheel failures. As it turns out, weight is the #1 cause of wheel failures on combines.

Wheel Design

Although some combines sport tracks or large super-single tires, most combines lurch off the assembly line with dolly duals. One bolt circle with 10 or 20 bolts holds the duals together and to the combine’s final drive. Dolly duals are notorious for cracking. And they usually fail during a busy harvest day at the farthest point from the field approach. These cracks start at the bolt holes and spiderweb outwards. It’s not uncommon to see entire centers detach from their rims and leave the wheel hanging.  

Manufacturing Methods

The cost-effective (fast) way of manufacturing wheels involves a stamping process. A massive press pushes metal into a die and into shape. Made this way, the wheel’s metal can become weakened—stretched or mushroomed. We’re talking fractions of an inch here. But a fraction of an inch is enough inconsistency to invite cracks and eventual wheel failures.

You have a cracked combine wheel. Now what?

You’ve dug your combine out of hibernation and are carefully inspecting its wheels under a bright, summer sky. (We all do this, right?) You happen to notice a few cracks on the auger-side inside dual. What’s your next step? Call NTS Tire Supply. We have an in-house wheel shop that can repair your wheels. To do this, we cut out the problem wheel's center and replace it with a larger diameter, sturdier one, and shotblast and powder coat the wheels to give it a like-new look.

3 Times When It Pays to Buy New Wheels instead of Repairing One

Repairing your cracked wheel is option #1. However, when a farmer calls us about cracked combine wheels, we always like to ask a few questions to get a clearer picture of the situation. Why? Because, in some cases, simply patching over the problem with a repair might not be the smartest solution.

1. Is this your first cracked wheel, or have you had this problem multiple times?
2. Have you upgraded your combine with a wider head or hopper extension?
3. How old is your combine? (Are the wheels getting up there in years?) Do you plan to run it for several more years?

These questions  help us determine the best option for your farm. Our repaired wheels are strong than factory spec, but if you have upgraded your combine with a larger head or hopper extension, the stock wheel and tire package may no longer be a fit for your combine. Likewise, if a farmer is tells us that he's experienced multiple cracked wheels on his combine, we have an important clue that a tire and wheel package upgrade may be his best bet.

Think Twice Before Buying A Used Wheel

At NTS, we stock both new and used combine wheels. And we just might have a used wheel on our lot that could replace your cracked wheel. It's tempting to snatch it up and save money. But how do you know you're not going to have the same cracking issue again? Remember the three questions above: Your factory-spec used wheel could develop a similar cracking issue and leave you stranded in the middle of harvest.

Your Best Solution to Cracked Combine Wheels: Upgrade to Straddle Duals

If you want to stick with a dual setup for you combine's front axle and you want to steer clear of wheel failures, invest in a set of straddle duals. Before we get to that, though, you have another option: switch your combine over to LSW super singles.

Read More: LSW Super Singles are Another Option That Virtually Eliminates Wheel Cracking Issues

Straddle duals use two bolt circles (in place of the single circle on OE Duals) to dissipate the stresses placed on the wheel over a much larger surface area. The inner bolt circle bolts the inner wheel to the combine hub; the outer bolt circle fastens the duals together. We make our own straddle duals, including an HD version (available in several common sizes) with a beefier design:

• 20% thicker steel on main wheel over O.E.
• A one-piece spun flange and tube eliminates welds that commonly fail on regular duals.
• More holding power with larger diameter tube/flange and 0.75" thicker threaded ring (on 20-hole wheels).  
• Bead flange reinforcements on main wheel.
• Durable powder coat finish.

Call NTS When You Have a Cracked Combine Wheel

Even the smallest crack will eventually work its way from a wheel's center to the rim and cause a catastrophic failure. If you spot a cracked combine wheel, your best bet is to call NTS Tire Supply. Our tire and wheel experts will work with you to determine the best fix for your cracking issue, whether that's a used wheel off our lot to get you up and running fast or a new set of straddle duals to fix the problem once and for all.