Article

Mismatching Dual Tires: A Sure-Fire Way to Kill Two Tires at Once

January 2014, TruckingInfo.com - WebXclusive

by Jim Park, Equipment Editor - Also by this author

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A recently released White Paper called "The Butterfly Effect on Tire Maintenance" from specialty tool manufacturer Innovative Products of America Inc., suggests there is real room for improvement when remounting a pair of used tires moved from another wheel position to a trailer.

"Fleets often make the mistake of using either inflation pressure or tread depth as an indicator of a proper match," the paper notes. "In fact, these two variables are independent of the diameter as a whole and if used alone will yield undesirable tread wear and fuel economy results."

This could be especially true if different brand, models, or tread patterns are assembled together.

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The Tire Comparator from IPA is a quick way to ensure the tires in a dual assembly are compatible.
The Tire Comparator from IPA is a quick way to ensure the tires in a dual assembly are compatible.

Even if two tires had the same tread depth, differences could exist in the tread underlay, the height of the sidewall or other places on the tire that will affect its circumference. Maintaining equal tread depth between the two tires may not be enough to ensure compatibility.

IPA offers a simple but clever solution to the challenge properly matching dual tires, the Tire Comparator. There are actually two versions of the caliper-like device, but both provide a clear visual indication of a mismatch condition. The tire tech simply checks the relative height of the two tires with IPA's device and makes a go or no-go decision.

The company also offers a tire inflator, the Mobile Tire Pressure Equalizer, that tops up inflation pressure in up to five tires at once, saving technician time and assuring equal pressure across all tires.

According to the IPA paper, the success of a tire pressure management system can fall back to the accuracy of the tire pressure gauge and the diligence of technician using it.

"When comparing two brand new tire gauges from the same manufacturer, accuracy often differs up to 3% right out of the box," IPA claims. "A gauge with +/- 3% accuracy will shift your reading by as much as 3 psi per tire at 100-psi target inflation."

While automatic tire inflation and tire pressure monitoring systems can assist in tracking problems on in-service vehicles, proper inflation before the vehicle leaves the shop as well as accurate gauges used during routine tire pressure testing as preventative maintenance measures can maximize your investment.

Fill four tires at the same time and all to exactly the same pressure with IPA's Mobile Tire Pressure Equalizer.
Fill four tires at the same time and all to exactly the same pressure with IPA's Mobile Tire Pressure Equalizer.

Consigning a tire from a previous wheel position to pre-graveyard trailer position need not mean giving up optimum mileage before retreading. But because trailer tires seldom get the attention they deserve, they are often given up for lost even as they are being bolted to the axle.

Mike Beckett of MD Alignment in Des Moines, Iowa, says there are no spec'ing options to improve the fate of trailer tires, so the duties seem to fall on the maintenance department's shoulders. Beckett sees the issue of mismatched tires cropping up constantly in his alignment shops.

"Mixing brands and models of casings in a dual assembly encourages irregular wear," he says. "The more focus on matched brands, models, circumference and inflation pressure, the better the tires will wear."

As tire costs continue to rise, along with fuel, it will become harder to ignore the living conditions of trailer tires. Lack of attention and basic maintenance can strip thousands of miles from even scabby old trailer tires, and increase the risk of a mission-crippling blowout.

"At about 1.9 cents per mile, tires are a significant maintenance cost for fleets," FMCSA's Flanigan reminds us. "The initial surveys we did in 2003 led us to conduct field tests of automatic tire inflations systems and tire pressure monitoring systems, and those tests proved our hypothesis that the cost recovery on those systems is there, and they provide ongoing cost savings and fuel economy improvements. In other words, they are worth the investment."

So, too, would be tools that ensure you're not killing both tires in a dual assemble through simple mismatching.


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Comments

  1. 1. Harvey Brodsky [ January 14, 2014 @ 02:05PM ]

    Anything Jim Parks writes is worthwhile reading. We need more folks like Jim to write articles that can save truckers money and headaches.
    Thanks, Jim, for another great article.

    Harvey Brodsky
    Managing Director
    Retread Tire Association

  2. 2. Ed Bluebaum [ January 14, 2014 @ 09:14PM ]

    Good article. The one point I cannot grasp is that the shorter tire is "dragged" to cover the same distance? The last time I noticed, the duals were bolted together and one could not drag the other, nor can it skip to catch up!

  3. 3. Jim Park [ January 14, 2014 @ 11:05PM ]

    Good question Ed. Here's an explanation. Let's assume the circumference of the taller tire is 100 inches -- to use a round number. But the shorter tire's circumference is 90 inches. For every rotation of the wheel, the taller tire will carry it 100 inches down the road. The shorter tire would normally travel 90 inches along the pavement, but because it is bolted to the 100-inch tire, it can't help by be dragged 10 inches to make up the same distance traveled. Hope that helps.

  4. 4. Fernando Dewes [ January 18, 2014 @ 05:12PM ]

    What is the sales Manager ou Sales director contact email of the dual dynamics Crossfire?

  5. 5. Carlton Biggs [ January 19, 2014 @ 09:15AM ]

    Interesting article and you are so right. I recently had two mismatched on a trailer and I watched them and I thought the same thing you are telling. The smaller one wore faster and eventually had a blow out.

  6. 6. Gary Kendall [ February 01, 2014 @ 05:10PM ]

    Sounds good on paper. But, I just cannot see how you are "dragging" the smaller tire when it is bolted solidly to the larger one. Now, if the tire is slipping on the wheel, that would be a different story. Put a chalk line across both tires and I guarantee you the chalk line will still be in the same place after any number of revolutions. Of course, I retired from driving over 5 years ago, and things do change.But you are going to have to prove this theory to me. Maybe the smaller tire is "growing" because of less load compared to the mating tire?

 

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