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PFA learns about tires and retreads at Desser Tire & Rubber Co.

PFA learns about tires and retreads at Desser Tire & Rubber Co.

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 June 2014- First off, let's get one Old Aviators Tale ("OAT") out of the way right now. It's safe to install retreaded aircraft tires on retractable gear airplanes.
For decades a rumor has circulated that retreaded tires should never be installed on a retractable gear airplane because the retreads came out bigger or would grow during use and would somehow jam in the wheelwells after being retracted. This falsehood caused many an owner to shy away from considering retreaded tires.
The rumor may have had some basis in fact years ago, but not anymore. I asked Desser President Steve Chlavin if there was any truth to this story. Chlavin replied, "Every retread must comply with the same specifications as a new tire."

This means that a Desser retread can't be any larger in circumference than a new tire. Some people get confused when they visually compare a newly retreaded tire to a brand-new tire; the retread will appear larger than the new tire. Here's why.

The retreading—the removal of the old rubber, preparation of the core (carcass) for new rubber, the winding on, balancing and baking of the new rubber—is done on a tire core that has already been stretched due to a normal inflation process when a tire is put into service. The new tire, when compared to the retread, is smaller since it hasn't yet been inflated and stretched.

Every tire stretches during the initial inflation. If you don't believe it, order a retread for your retractable landing gear airplane, mount the tire and inflate it in accordance with the aircraft service manual.
You'll have to wait 24 hours for the tire to reach its dimension since stretch averages three percent, then retract the gear into the wheelwell. If you have any doubts about the fit of a Desser retread in the wheelwell, return it for a full refund.

Need further proof? Beechcraft service manuals contain a sentence that while not recommending the use of retreads advises that they may be used as long as the retreading was done by an FAA approved repair station in accordance with Technical Standard Order (TSO) C62c (now C62e). This TSO is the same order that regulates new tire construction. A retread must have the same measured outside circumference as a new tire.

So if a retread isn't an operational concern, and since retreads are less expensive than new tires of the same size and ply rating, why is there a reluctance to buy retreads?
What about the alligator argument?

When I asked Chlavin about this hesitation, he replied that one anti-retread argument originates from people that cite examples of huge chunks of tread—sometimes called "alligators"—that are often seen along highways. These have been thrown off of retreaded tires used by over-the-road trucks.

Chlavin explained that any retreaded—or new—tire will throw tread if it gets too hot. These "alligators" are thrown off of truck tires that have overheated due to continued running after the tire has suffered a puncture and is deflated; since the load of the deflated tire is taken up by the adjacent tire, the driver doesn't know the tire is deflated and continues to drive.

Eventually the tire gets very hot and the tread departs. That never happens on an airplane if it's properly maintained.
To further assure us of the soundness of retreaded tires, our group followed a tire core through the process.

Test after test
Upon receipt every tire sent to Desser is visually inspected for wear, flat spots and sidewall cracking. According to Gus Segura, Desser's Repair Station Quality Assurance Manager, wear into two fabric plies (cords) is acceptable for transport- or commercial-grade tires—if all other checks are good. GA tires with ply (cord) wear cannot be retreaded.

The next check on tubeless tires (there aren't many of these used on GA airplanes) is an air pressure test to determine if the liner is good. The liner is the inner part of the tire. Air pressure is applied between the plies for approximately 30 minutes; only limited leakage past the liner is permitted. "The liner is the key factor [in the soundness of the tire]," said Segura.

After passing the liner leakage test the next step is to remove what Segura calls the "old" rubber. Each tire is mounted on a mandrel that swings the tire in the proper sized arc for that size tire back and forth across a many-toothed grinding wheel.

After the correct amount of rubber is removed, the tire surface is rough and clean. The surface must be kept clean to insure a good bond between the tire carcass and the new rubber.

The tire is again mounted on a mandrel in front of a large, computer controlled machine. The operator selects the proper rubber program for the tire—the Orbitread process is used—and inserts rubber into the machine where it's heated to approximately 230 degrees F before it's spit out in a strip that's approximately two inches wide and slowly wound onto the rotating tire. The operator applies pressure by hand as each strip is laid down.

After 90 to 120 seconds the thickness of the layers is checked at numerous points around each tire. If it's correct the tire is passed on to the pre-balance station where balance is checked. If needed additional strips of rubber are applied to bring the balance into line.

After pre-balancing is completed the tire is put on a rack and moved to the molding area.

Segura said the company has 60 molds of various sizes. Each mold is specially made to simulate a tire rim on the inside and establish the outside dimension and tread pattern. "We have equipment from five or six retreaders that have gone out of business," said Ken Faire, Vice President at Desser.

The pre-molded tire is mounted on the rim and put in the mold. Air pressure is applied to push the casing out against the mold where it's held at temperatures of 300 to 305 degrees F for 70 to 120 minutes depending on the size of the tire. This bonds and shapes the retread rubber.

Final testing: laser shearography
After cooling, each tire is inspected using a process called interferometric laser shearography. According to the Desser website, "Laser shearography is very sensitive to slight changes in surface strain due to subsurface flaws, and it is able to detect imperfections and defects such as belt-edge separations, bead blisters, undercure, liner separation and broken cord and ply construction in aircraft tires."

There's no FAA requirement to conduct this type of testing, but Segura told me that the shearography testing inspects each Desser retread to seven different readings that will detect unseen shears and separations.

Once a tire passes this final test, it's passed on to one more station for the final balance check and adjustment if needed.

Lastly the proper paperwork is generated (Form FAA 8130-3, Authorized Release Certificate, Airworthiness Approval Tag) and the tire is tagged.

This process has been fine-tuned over years, and Desser recaps around 25,000 tires a year.

Core suitability
Some owners ask if it's smart to reuse a tire core. Segura answers by saying that Desser believes a good core can go through five retreadings; some business jet and airliner tires are recapped at least eight times before the core is retired.

According to Chlavin, the standard for GA tires is one retreading. There's a core suitability checklist on the Desser website; see Resources at the end of this article for more information.

Purchase options
Owners have a number of recap purchase options. First, they can send in their own tires and have them recapped to Desser standards. That way they know the history of the tire. Segura said the turnaround time is around two weeks.

Customers can also send in their tire cores and exchange them for certified retreads that have the same make core. For example, if you like Michelin tires, you can specify that you want a recap with a Michelin core. Chlavin told me that Desser does its best to accommodate each request.

Another option is to send in your cores and have the value applied to a new tire purchase.

Lastly, you can send in your cores and ask for the cash value.

You want new tires? Desser has those, too

Desser is one of the premier FAA approved tire retreading companies in the United States, yet retreading is only part of Desser's business model. In addition to the 50,000 square foot facility in Montebello, it also has a 100,000 square foot facility in Memphis, Tenn.

The company shipped over 100,000 new tires and specialty tires last year and is a stocking dealer for Dunlop, Goodyear, Michelin, Condor, Specialty Tires of America (McCreary) and Desser's own Aero Classic Specialty Tires and Tubes.

All of these tires—and all Desser retreads—can be ordered directly from Desser through its website or through stocking dealers.

Over 150 tires and plies are available from Desser. Desser Tire also offers free shipping (within the 48 contiguous United States) on all orders over $100.

History and growth of the company
Desser was first established in 1920 as a scrap rubber dealer; by 1941 the name was changed to Desser Tire and Rubber. At the close of World War II, Myron Chlavin, Steve's father, started buying aircraft tires. Steve Chlavin began working for his father after high school and is now president of the company.

Desser Tire and Rubber grew with the acquisition of Omni Air and later with the purchase of the wheel and brake repair station of Aero Wheel and Brake in 1994. Aero Wheel and Brake provides a full wheel and brake services for Boeing, Lockheed, Honeywell, Raytheon and other corporate clients.

In 1998 Ken Faire came over from Herber Aircraft with the purchase of Cee Bailey's Aircraft Plastics.

Desser also has held contracts to provide wheels and brakes for the SR-71, U-2 and the NASA 747 used to transport the Space Shuttle to Florida. Since shipping of large tire/wheel combinations is costly, a pickup and delivery service is provided in the Southern California area.

Cee Bailey's windshields and support products
Desser manufactures windshields and side windows as needed for a number of OEMs under the Cee Bailey's name. Replacement windshields and side windows are available for almost all GA singles and twins in clear, green, or the newer solar gray tints.

Other support products sold under the Cee Bailey's name include cowl plugs, CeeShade sunshields, Rosen Sunvisors, and window and windshield cleaning and care products. (Visit Cee Bailey's Aircraft Plastics at ceebaileys.com. —Ed.)

LeakGuard® tubes, vacuum system components, batteries and more
In 2002 Desser started manufacturing the LeakGuard inner tube. Since tires and tubes stretch during use, a new inner tube should always be installed whenever a new tire is mounted. Natural rubber tubes were the standard for decades in spite of the fact that they leaked; and since underinflation results in shorter tire life, these tubes needed to reinflated often.

The LeakGuard tube is made of butyl rubber and is much more leak resistant. The only drawback with the butyl rubber LeakGuard tube is how stiff it gets in colder weather. "In Alaska, it is hard to sell the butyl tube, as the natural rubber tube takes a colder temperature coefficient range than the butyl," said Faire.

Desser also stocks Rapco products including brake discs, rivets and pads; and vacuum system components such as suction and pressure regulators, filters, dry air pumps and isolation check valves for multi-engine vacuum systems.

Concorde and Gill Batteries in the most common flooded cell and sealed battery configurations are in stock, as well as Gill and Concorde chargers and capacity testing equipment.
Hard-to-find tires

I needed a set of original smooth tread 8.00 x 4 tires for the 1939 Piper J-3 I was rebuilding. Fortunately, I discovered that Desser makes these—and during our recent visit to Montebello, we found they also make other obsolete and hard-to-find tires.

The Cub tires weren't inexpensive, but they were available—and they added that final right touch to the restoration. The owner couldn't be happier.

Desser is the go-to place to get tires of all shapes and sizes. I found that the free shipping on all orders over $100 combined with very competitive prices to be a powerful incentive for putting the Desser URL in my "Favorite Aero Parts" folder.

Steve Ells has been an A&P/IA for 39 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He's a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and lives in Paso Robles, Calif. with his wife Audrey. Send questions and comments to .

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Resources
Desser Tire & Rubber Co., Inc.
desser.com
Tire Casing Inspection Checklist
desser.com/casingform.pdf


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