Category: USEPA

Tire Retreading Facts & Information

In the early twentieth century America’s unpaved and hazardous roadways were incredibly rough on the pneumatic tires running on bicycles, motorcycles, automobiles and commercial trucks.  If these tires were not damaged prematurely, they were still lucky enough to average about 1,000 miles before wearing out.

One of the first methods invented for extending the life of tires was the process of retreading the casings.  Strips of uncured rubber were added to the casing and then vulcanized, but this technique was unreliable because only parts of the casing could be cured at one time which led to unequaled curing and a defective retread.

In 1912, Marion Oliver developed and patented a tire retreading method known as pre-cure. This process involved buffing the tire to the fabric and then placing a pre-cured tread on top.  This process has become the most widely used and accepted practice of retreading tires to this day.  The pre-cured tread, because of advanced proprietary rubber compounds and the lower curing temperature needed to cure, can average just about the same mileage as a new tire.  Today there are over 650 retread shops in the U.S. and 90%-95% of them use the pre-cure process.

With the continued improvement in today’s technologies for inspecting tire casings for retreading, the overall failure rate has dramatically declined and the safety of a retreaded tire is fairly comparable to a new tire.  Most of the same types of machinery are used for each.  The economical and environmental benefits of retreading are more important than ever, with fleets and mining operations pressed to reduce costs as well as comply with environmental regulations enforced by the Federal Government.

RETREADING IS GOOD FOR THE ENVIRONMENT

  • Tires are a petrochemical commodity, because of this it takes about 22 gallons of oil to produce a commercial truck tire
  • It only takes about 7 gallons of oil to produce a commercial truck tire retread
  • It could take up to 500 gallons of oil to produce one OTR tire
  • Buffed rubber dust is recycled into many things such as playground surfaces, rubber welcome mats and alternative energy
  • Retreading reduces carbon dioxide emissions as well as other harmful and toxic substances
  • Tread rubber manufacturers have many designs that are now SmartWay verified

RETREADING IS ECONOMICAL AND SAFE

  • Nearly 90% of all aircraft in the world use retreaded tires
  • The U.S. Federal Government has mandated that all government fleets use retreads
  • Millions of casings are retreaded every year, saving billions of dollars across many industries such as trucking, mining, construction, air transportation, cargo handling and industrial applications

Tire Regulation Agencies & Definitions

There are many rules and regulations for commercial tires in the U.S. that are implemented and enforced to ensure the safety of all motorists on the nation’s highways. Both commercial tire dealers and fleet owners are required to stay educated and informed on these regulations as they most often are updated on an annual basis.

The Code of Federal Regulations (CFR) 393.75 describes eight specific parts involving commercial truck tires and it stated in full below.

(a) No motor vehicle shall be operated on any tire that—

(1) Has body ply or belt material exposed through the tread or sidewall,

(2) Has any tread or sidewall separation,

(3) Is flat or has an audible leak, or

(4) Has a cut to the extent that the ply or belt material is exposed.

(b) Any tire on the front wheels of a bus, truck, or truck tractor shall have a tread groove pattern depth of at least 4⁄32of an inch when measured at any point on a major tread groove. The measurements shall not be made where tie bars, humps, or fillets are located.

(c) Except as provided in paragraph (b) of this section, tires shall have a tread groove pattern depth of at least 2⁄32 of an inch when measured in a major tread groove. The measurement shall not be made where tie bars, humps or fillets are located.

(d) No bus shall be operated with regrooved, recapped or retreaded tires on the front wheels.

(e) A regrooved tire with a load-carrying capacity equal to or greater than 2,232 kg (4,920 pounds) shall not be used on the front wheels of any truck or truck tractor.

(f) No motor vehicle may be operated with speed-restricted tires labeled with a maximum speed of 55 mph or less in accordance with S6.5(e) of FMVSS No. 119 at speeds that exceed the rated limit of the tire.

(g) Tire loading restrictions (except on manufactured homes). No motor vehicle (except manufactured homes, which are governed by paragraph (h) of this section) shall be operated with tires that carry a weight greater than that marked on the sidewall of the tire or, in the absence of such a marking, a weight greater than that specified for the tires in any of the publications of any of the organizations listed in Federal Motor Vehicle Safety Standard No. 119 (49 CFR 571.119, S5.1(b)) unless:

(1) The vehicle is being operated under the terms of a special permit issued by the State; and

(2) The vehicle is being operated at a reduced speed to compensate for the tire loading in excess of the manufacturer’s rated capacity for the tire. In no case shall the speed exceed 80 km/hr (50 mph).

(h)(1) Tire loading restrictions for manufactured homes built before January 1, 2002. Manufactured homes that are labeled pursuant to 24 CFR 3282.362(c)(2)(i) before January 1, 2002, must not be transported on tires that are loaded more than 18 percent over the load rating marked on the sidewall of the tire or, in the absence of such a marking, more than 18 percent over the load rating specified in any of the publications of any of the organizations listed in FMVSS No. 119 (49 CFR 571.119, S5.1(b)). Manufactured homes labeled before January 1, 2002, transported on tires overloaded by 9 percent or more must not be operated at speeds exceeding 80 km/hr (50 mph).

(2) Tire loading restrictions for manufactured homes built on or after January 1, 2002. Manufactured homes that are labeled pursuant to 24 CFR 3282.362(c)(2)(i) on or after January 1, 2002, must not be transported on tires loaded beyond the load rating marked on the sidewall of the tire or, in the absence of such a marking, the load rating specified in any of the publications of any of the organizations listed in FMVSS No. 119 (49 CFR 571.119, S5.1(b)).

(i) Tire inflation pressure. (1) No motor vehicle shall be operated on a tire which has a cold inflation pressure less than that specified for the load being carried.

(2) If the inflation pressure of the tire has been increased by heat because of the recent operation of the vehicle, the cold inflation pressure shall be estimated by subtracting the inflation buildup factor shown in Table 1 from the measured inflation pressure.

inflation-pressure-management

Source: U.S. Government Publishing Office

The Commercial Vehicle Safety Alliance (CVSA) is an international not-for-profit organization comprised of local, state, provincial, territorial and federal motor carrier safety officials and industry representatives from the United States, Canada, and Mexico.

Approximately 4 million commercial motor vehicle inspections are conducted every year throughout North America to ensure the large trucks and buses driving on our roadways are operating safely. Specially trained inspectors in each state, jurisdiction, territory and province inspect commercial motor vehicles based on inspection procedures and criteria created by CVSA, known as the North American Standard Inspection Program.

There are seven levels of inspections ranging from the most comprehensive Level I Inspection, which evaluates both the driver and vehicle, to inspection levels with a more specific area of focus, such as the Level VI Inspection for hazardous materials or dangerous goods.

Roadside inspections are conducted by highly-qualified, specially-trained and certified state, provincial, territorial, and federal law enforcement personnel.

The North American Standard Inspection Program is NOT intended or designed to be a periodic inspection program or a preventative maintenance program for carriers and drivers. However, it does provide a snapshot of CMV maintenance, and determines the effectiveness of a company or driver’s CMV maintenance and safety management program. The data collected helps state, provincial, territorial, and federal governments in the U.S., Canada, and Mexico determine which transportation companies will be selected for review.

north-american-standard-inspection-procedures

Source: Commercial Vehicle Safety Alliance

EPA’s SmartWay program helps companies advance supply chain sustainability by measuring, benchmarking, and freight transportation efficiency.

Launched in 2004, this voluntary public-private program:

  • provides a comprehensive and well-recognized system for tracking, documenting and sharing information about fuel use and freight emissions across supply chains
  • helps companies identify and select more efficient freight carriers, transport modes, equipment, and operational strategies to improve supply chain sustainability and lower costs from goods movement
  • supports global energy security and offsets environmental risk for companies and countries
  • reduces freight transportation-related climate change and air pollutant emissions by accelerating the use of advanced fuel-saving technologies
  • is supported by major transportation industry associations, environmental groups, state and local governments, international agencies, and the corporate community

SmartWay publishes a verified list of new tires and retreads that meet certain criteria that will ultimately cut down on fuel costs and harmful NOx emissions. The EPA has demonstrated that certain low rolling resistance (LRR) tires and retread technologies can reduce both costs and emissions for long-haul class 8 tractor-trailers by 3% or more.

Below is the SmartWay List for Low Rolling Resistance (LRR) of new and retread tire technologies published in December, 2016:

Source: United States Environmental Protection Agency

Executive Order 13149 of April 21, 2000

Greening the Government Through Federal Fleet and Transportation Efficiency.

“Consistent with Executive Order 13101 and RCRA section 6962, in acquiring and maintaining motor vehicles, agencies shall acquire and use United States EPA-designated Comprehensive Procurement Guideline items, including but not limited to retread tires, when such products are reasonably available and meet applicable performance standards. In addition, Federal agencies should consider acquiring other recycled content products, such as tires containing a minimum of 5–10 percent post-consumer recovered rubber.”

Scrap Tire Research and Education Foundation

The Scrap Tire Research and Education Foundation, Inc. is a non-profit research foundation established to support basic and applied research and appropriate educational activities on issues relating to the sound handling and utilization of waste or scrap tires.

The foundation was organized in late 1992 and operates in cooperation with the Rubber Manufacturers Association which is recognized as the leading organization devoted to promoting economically viable and environmentally sound uses for scrap tires.

The goals of promoting scrap tires as a valuable commodity in all ways that are economically and environmentally sound have continually been met in many important areas such as civil engineering, rubber modified asphalt, artificial reefs, alternative fuels and more.

Website: http://stref.org/

The RMA and STREF offer a comprehensive list of state scrap tire regulators here.  Listed below is an abbreviated version for quick reference:

Alaska
Alaska Department of Environmental Conservation
Solid Waste Program
555 Cordova Street
Anchorage, AK 99501

Alabama
Department of Environmental Management
PO Box 301463
Montgomery, AL 36130-1463

Arkansas
Arkansas Department of Environmental Quality
5301 Northshore Drive North
Little Rock, AR 72118

Arizona
Arizona Department of Environmental Quality
1110 West Washington Street
Phoenix, AZ 85007

California
Department of Resources Recycling and Recovery (CalRecycle)
1001 I Street–P.O. Box 4025
Sacramento, CA 95812-4025

Colorado
Colorado Department of Public Health and Environment Protection
4300 Cherry Creek Drive South
Denver, CO 80246

Connecticut
Connecticut Department of Environmental Protection
79 Elm Street
Hartford, CT 06106

Delaware
DNREC Division of Waste and Hazardous Substances
89 Kings Highway
Dover, DE 19901

Florida
Florida Department of Environmental Protection
MS 4565
2600 Blair Stone Road
Tallahassee, FL 32339

Georgia
Environmental Protection Division
2 Martin Luther King Jr. Drive
Suite 1154 East
Atlanta, GA 30334

Hawaii
Hawaii Department of Health
919 Ala Moana Boulevard
Room 212
Honolulu, HI 96814

Iowa
Iowa Department of Natural Resources
502 East Ninth Street
Des Moines, IA 50319

Idaho
Idaho Department of Environmental Quality
1410 N. Hilton
Boise, ID 83706

Illinois
Illinois Environmental Protection Agency
1021 North Grand Avenue East
PO Box 19276
Springfield, IL 62794

Indiana
IDEM/OPPTA
100 N. Senate Ave.
MC 64-00 IGCS West 041
Indianapolis, IN 46204

Kansas
Kansas Dept. of Health and the Environment
1000 Southwest Jackson
Suite 320
Topeka, KS 66612

Kentucky
Division of Waste Management
200 Fair Oaks Land
2nd Floor
Frankfort, KY 40601

Louisiana
Louisiana Dept. of Environmental Quality
P.O. Box 4303
Baton Rouge, LA 70821

Massachusetts
Massachusetts Executive Office of Environmental Protection
One Winter Street
Boston, MA 02108

Maryland
Maryland Dept. of Environment
1800 Washington Blvd.
Suite 605
Baltimore, MD 21230

Maine
Maine Dept. of Environmental Protection
312 Canco Road
Portland, ME 04103

Michigan
Michigan Dept. of Natural Resources and Environment
P.O. Box 30241
Lansing, MI 48909

Minnesota
Minnesota Pollution Control Agency
520 Lafayette Road North
St. Paul, MN 55155

Missouri
Missouri Dept. of Natural Resources
P.O. Box 176
Jefferson City, MO 65102

Mississippi
Office of Pollution Control Solid Waste Policy
Planning and Grants Branch
P.O. Box 2261
Jackson, MS 39225

Montana
Montana DEQ
P.O. Box 200901
Helena, MT 59620

North Carolina
North Carolina Dept. of Environmental and Natural Resources
1646 Mail Service Center
Raleigh, NC 27699

North Dakota
North Dakota Dept. of Health
Division of Waste Management
918 East Divide Ave.
3rd Floor
Bismarck, ND 58501

Nebraska
Nebraska Dept. of Environmental Quality
P.O. Box 98922
Lincoln, NE 68509

New Hampshire
Dept. of Environmental Services
29 Hazen Drive
Concord, NH 03301

New Jersey
NJDEP
Bureau of Recycling and Planning
401 East State Street
Trenton, NJ 08625

New Mexico
New Mexico Environment Department
Solid Waste Bureau
Harold Runnels Building
1190 St. Francis Drive/P.O. Box 5469
Santa Fe, NM 87505

Nevada
Nevada DEP Bureau of Waste Management
901 S. Stewart Street
Ste. 4001
Carson City, NV 89701

New York
NYSDEC
Division of Materials Management
Bureau of Permitting and Planning
625 Broadway Albany, NY 12233

Ohio
Ohio Environmental Protection Agency
P.O. Box 1049
Columbus, OH 43216

Oklahoma
Oklahoma Dept. of Environmental Quality
P.O. Box 1677
Oklahoma City, OK 73101

Oregon
Oregon Dept. of Environmental Quality
811 S. W. 6th Avenue
9th Floor
Portland, OR 97204

Pennsylvania
Pennsylvania Dept. of Environmental Protection
400 Market Street
14th Floor Harrisburg
PA 17105

Rhode Island
Rhode Island Dept. of Environmental Management
235 Promenade Street
Providence, RI 02908

South Carolina
South Carolina Dept. of Health and Environmental Control
2600 Bull Street
Columbia, SC 29201

South Dakota
South Dakota Dept. of Environment and Natural Resources
523 East Capitol Avenue
Pierre, SD 57501

Tennessee
Division of Solid Waste Management/TDEC
William R. Snodgrass Tennessee Tower
14th Floor
312 Rosa L Parks Avenue
Nashville, TN 37243

Texas
Texas Commission of Environmental Quality
Waste Permits Division
P.O. Box 13087
MC-174
Austin, TX 78711

Utah
Utah Dept. of Environmental Quality
P.O. Box 144880
Salt Lake City, UT 84114

Virginia
Virginia Dept. of EnvironmentalQuality
Waste Tire Program
P.O. Box 1105
Richmond, VA 23218

Vermont
Solid Waste Management Program
1 National Life Drive
Davis 1
Montpelier, VT 05620

Washington
Washington State DOE Waste 2 Resources Program
Northwest Regional Office 3190
160th Ave., SE
Bellevue, WA 98008-5452

Wisconsin
Wisconsin DEM
P.O. Box 7921
Madison, WI 53707

West Virginia
WV DEP Rehabilitation Environmental Action Plan
601 57th Street, SE
Suite 1031
Charleston, WV 25304

Wyoming
Solid Waste Permitting and Corrective Action
152 North Durbin
Suite 100
Casper, WY 82601

Aircraft Tire Retreading

  • Nearly 90% of all aircraft tires now in use in the United States are retreads.
  • Millions of dollars per year are saved because of aircraft tire retreading.
  • According to the United States Environmental Protection Agency; Air Force One, the official plane of the President of the United States, uses retread aircraft casings.

airplane-landing-1486116-1279x854

Federal Aviation Administration Advisory Circular AC 145 4A
(Subject: Inspection, Retread, Repair, and Alterations of Aircraft Tires)

1. PURPOSE. This advisory circular (AC) provides guidance for the development, qualification, and approval of bias and radial aircraft tire retreads, their repair and process specifications, and the use of special nondestructive inspection (NDI) techniques. This material is neither mandatory nor regulatory in nature and does not constitute a regulation. It describes acceptable means, but not the only means, for developing specifications to be submitted to the proper Federal Aviation Administration (FAA) office for approval. The FAA will consider other methods of demonstrating compliance that an applicant may elect to present. Terms such as “shall” and “must” are used only in the sense of ensuring applicability of this particular method of compliance when the methods of compliance described in this document are used.

2. CANCELLATION. AC 145-4, Inspection, Retread, Repair, and Alterations of Aircraft Tires, dated September 27, 1982, is canceled.

3. RELATED REGULATIONS AND REFERENCES (current editions). a. Title 14 of the Code of Federal Regulations (14 CFR). (1) Part 21, Subpart O, Technical Standard Order Authorizations. (2) Part 23, Airworthiness Standards: Normal, utility, acrobatic, and commuter category airplanes. (3) Part 25, Airworthiness Standards: Transport category airplanes. (4) Part 27, Airworthiness Standards: Normal category rotorcraft. (5) Part 29, Airworthiness Standards: Transport category rotorcraft. (6) Part 43, Maintenance, preventive maintenance, rebuilding, and alteration. (7) Part 145, Repair stations. b. AC. AC 20-97, Aircraft Tire Maintenance and Operational Practices.  c. Technical Standard Order (TSO). TSO-C62, Tires. d. Industry Documents. (1) ARP 4834, Aircraft Tire Retreading Practice—Bias and Radial. (2) AS 4833, Aircraft New Tire Standard—Bias and Radial. (3) TRA, Tire and Rim Association Aircraft Yearbook. (4) ETRTO, European Tire and Rim Technical Organization Standards Manual.

4. DEFINITIONS. a. Retreading. The term retreading refers to the methods of restoring a worn tire by renewing the tread area or by renewing the tread area plus one or both sidewalls. Repairs are included in the tire retreading process. b. Specification. Documents approved by the Administrator containing information for performing specialized maintenance, such as retreading of tires. NOTE: Repair stations with limited ratings for specialized services are required under part 145, § 145.61(c) to include a specification on their operations specifications. c. Retread Level (R-Level) Escalation. R-level escalation is the process used to verify that a population of retreaded tires is suitable for an additional service life. d. Load Rating. Load rating is the maximum permissible load at a specific inflation pressure. The rated load combined with the rated inflation pressure will be used when selecting tires for application to an aircraft and for testing to the performance requirements of this document. e. Ply Rating. This term is used to identify the maximum recommended load rating and inflation pressure for a specified tire. It is an index of tire strength. f. Speed Rating. The speed rating is the maximum takeoff speed to which the tire has been tested. g. Bias Tire. A pneumatic tire in which the ply cords extend to the beads and are laid at alternate angles substantially less than 90 degrees to the centerline of the tread. h. Radial Tire. A pneumatic tire in which the ply cords extend to the beads and are laid substantially at 90 degrees to the centerline of the tread, the casing being stabilized by an essentially inextensible circumferential belt. i. Casing. The casing is the structural part of the tire. j. Compatible Casing. A compatible casing for retreading is one capable of passing all retreader acceptance criteria for that size, ply rating, and speed rating.  k. Skid Depth. The distance between the tread surface and the deepest groove as measured in the mold. l. Maximum Outside Diameter (D0). For the bias tire, it is the maximum new (ungrown) diameter along the centerline of the tire as denoted in TRA and ETRTO. For the radial tire, it is the maximum new (ungrown) diameter of its bias tire equivalent.

5. BACKGROUND. In parallel with the introduction and installation of new radial tire designs on the U.S. civil aircraft fleet, the FAA initiated a project to update appropriate safety standards and advisory support material. This includes revisions to TSO-C62, AC 145-4, and AC 20-97. The retreader’s quality and escalation plans are based in part on the manner in which the airline operator maintains the retread tire in service. The long term integrity and reliability of the retread tire is significantly influenced by the inflation pressure schedule, the frequency of tire pressure checks, and the identification of tire removal conditions that may impact the continued airworthiness of the tire. This revision will ensure that repair stations which retread bias and/or radial tires, and aircraft operators who use these tires, have proper guidance which assures the continued performance of a tire through testing, as originally approved under the TSO (and requirements under part 43, § 43.13), and provides the basis for the development of a specification covering the inspection, retread, and repair of tires, as set forth under part 145.

6. SPECIFICATION REQUIREMENTS. a. Title 14 CFR Requirements. (1) Repair Station. A repair station that is certificated to retread aircraft tires is required by § 145.61(c). to perform that work in accordance with a specification approved by the FAA or in accordance with an operator’s manual as outlined in § 43.13(c). (2) Operator. A holder of an air carrier operating certificate or an operator with a 14 CFR part 125 operating certificate may adopt a retreading agency’s approved specification and include it as a part of its manual as outlined in 14 CFR part 121, 125, or 135. b. Specification Requirements. The retreader of bias or radial aircraft tires is required to establish maintenance and repair practices, including special nondestructive inspection techniques and retreading procedures. These practices could be techniques defined, developed, and validated by the retreader and approved by the FAA or from information provided by the tire manufacturer. The minimum requirements and issues to be addressed for a specification that would be developed and submitted for FAA approval by a repair station and retreader are identified within this document. c. Applicability. For retreading bias and radial aircraft tires manufactured under TSO-C62, a specification and requirements defined here shall be developed and complied with by the repair station and retreader for all repaired and retreaded tires after the effective date of this AC. Bias tires that were manufactured to prior TSO standards may be repaired in accordance with maintenance instructions identified under AC 145-4, dated September 27, 1982. However, further escalation of these existing tires should comply with the escalation of these requirements.

7. MARKING.  a. Retread Identification. The following minimum information must appear in permanent markings between the wearing surface and the edge of the newly applied rubber. (1) The retreader’s name or registered trademark. (2) The retread plant identification code. (3) The month and year the retread was performed. (4) The letter “R” followed by the number of times the casing has been retreaded. b. Casing Identification. Retread processing may destroy some or all of the casing identification. The following information must be restored if removed during retreading: (1) Airworthiness compliance markings (only restore at the direction of the original casing manufacturer); (2) Size and load rating; (3) Casing manufacturer’s name or trademark; (4) Ply rating; (5) Casing manufacturer’s plant code; (6) Date of manufacture; (7) Serial number; (8) Speed rating; (9) Casing manufacturer’s part number; and (10) Tire type. Tires requiring a tube in their operation shall be marked with the words “Tube Type.” c. Regrading Procedure. (1) The ply rating, load rating, and/or speed rating on either the casing or the retread may be decreased without approval. All performance and qualification parameters under the new rating must be met. (2) If the ply rating, load rating, and speed rating markings of the casing do not agree with the retread qualification status, they must be buffed off and the correct markings applied. (3) The casing manufacturer’s part number must not be altered without the original casing manufacturer’s approval. (4) Any upgrading in the speed rating or load rating, or any change in the tire size from the qualified new tire size will be considered a new product. d. Marking Maximum Cut Limit Repairs. Casings containing maximum allowable cut limit repairs in the tread area should be identified with a sidewall brand in line with the repair. The guidelines and conditions under which this brand is applied should be specified in the retreader’s specification.

8. CASING SELECTION. The new tire casing must be approved by the FAA. Unless otherwise restricted by the tire manufacturer or FAA, any eligible tire may be retreaded provided it meets the inspection and defect limitation criteria, and has met the R-level escalation inspection and test criteria established in the FAA-certificated repair station and the retreader’s FAA-approved specification. a. Inspection. The following are commonly available NDI techniques that should be used when necessary and as specified in this document. (1) Visual. All tires should be visually inspected in the tread, sidewall, bead, and liner areas for conditions that need repair or which require that the tire be scrapped. (2) Air Injection. Tubeless tires may be air injected with a dry filtered gas (e.g., air or nitrogen) to inspect the casing for proper venting, separations, bead and liner condition, etc. (3) NDI. Holography, shearography, ultrasonic, X-ray, and other NDI methods should be used as necessary and where applicable. b. Disposition of Tire Casings. (1) Acceptable Casings. Tires which meet the acceptable limits for repair listed in the FAA-approved retreader’s specification may be repaired/retreaded and returned to service. (2) Unacceptable Casings. Tires that fail the acceptable limits for repair listed in the retreader’s specification should be rejected from further aircraft use. Casings not returned to the customer should have all airworthiness compliance markings removed. Removal of the serial number is at the discretion of the retreader. Further, the casing should be marked in a conspicuous manner indicating the casing is not suitable for aircraft use.

9. REPAIR PROCESS. Repairs are permitted if the anomaly (i.e., damage or fatigue) does not exceed limitations specified by the tire manufacturer or the rejection criteria identified in the repair station and retreader’s specification, as approved by the FAA. Maximum permissible repairs identified in the process specification shall be validated by tests and/or analysis for FAA approval before returning to service. The specification shall include each of the repair types for bias and radial tires, as identified in the Appendix 1, and additional repairs identified by the retreader.

10. RETREADING PROCESS. The retreading process includes removal of old material, renewing the tread area, and curing and bonding of the new material to the casing. A retreading process identified by the repair station and retreader must be provided in the specification for approval by the FAA. Provisions should be included that assure that the retreaded tire weight will not exceed the maximum allowable weight (where it has been determined by the landing gear or airframe requirements established by the aircraft manufacturer).

11. QUALIFICATION TESTING. a. General. (1) The test procedures described herein are intended to ensure compatibility between the original tire casing and newly applied retread. This qualification test is required with the first (R-1) application of a new tread and as otherwise specified in this AC. The retread should not fail the applicable dynamometer tests specified herein nor have any signs of structural deterioration other than normal expected tread wear except when the overload takeoff cycle is run last (see paragraph 11b below). Casings selected for retread tests should have at least 80 percent of their new molded tire skid depth removed by wear (i.e., worn by aircraft usage). (2) Design and construction differences between radial tires of different manufacturers dictate that retread dynamometer testing be conducted on one sample of each manufacturer’s radial tire casing at the first (R-1) application of a new tread. Qualification of bias tire retreads on a single manufacturer’s casing qualifies the retread on other manufacturer’s compatible casings of the same size, ply rating and speed rating. b. Dynamometer Test Cycles. The retread test tire shall satisfactorily withstand 61-dynamometer cycles as specified in TSO-C62 , as a demonstration of overall performance. The 61-dynamometer cycles shall consist of 50-takeoff cycles, 8-taxi cycles at rated load, 2-taxi cycles at 1.2 times rated load, and 1-overload takeoff cycle starting at 1.5 times rated load. Good condition of the tire tread is not required after completion of the overload takeoff cycle if it is run last. The sequence of the cycles is optional. However, if the overload takeoff cycle is not run last, the tire must not show detectable signs of deterioration after the cycle completion, other than normal expected tread surface abrasion. A single tire specimen must be used to complete these cycles. c. Requalification Tests. A retread tire that has been altered, and which has changes in materials, design and/or manufacturing processes that could adversely affect the performance and reliability of the tire, shall be requalified to the dynamometer tests described in paragraph 11b regardless of the escalation level. Examples of such changes include, but are not limited to, changes in tread construction, such as the number or composition of tread reinforcing and/or protector plies, tread compound formulation, number and location of tread grooves, and increases in skid depth and/or tread gauge. Requalification by similarity, as discussed in paragraphs (1) and (2) below, applies to all bias tires that are compatible with the new tread design and/or material change. However, requalification by similarity for radial tires only applies to tires of comparable design by a single manufacturer. Requalification by similarity is not allowed for radial tires from different manufacturers. (1) Requalification by Similarity (Based on Load Rating). Requalification of a given load rated retreaded tire required as a result of a tread design or material change will automatically qualify the same changes in a lesser load rated retreaded tire of the same size, speed rating, and skid depth provided the lesser load rated retreaded tire has been qualified to the applicable requirements specified in this standard. fects multiple sizes may be made by similarity providing that: (a) Five representative sizes, including tires of the highest load, speed rating, and angular velocity, have been qualified to the minimum performance standard with the change. (b) The data in support of the change in the listed sizes should be submitted to and approved by the appropriate FAA office. d. Overpressure. A retreaded tire, processed in a manner similar to the example tested on the dynamometer, shall successfully withstand a hydrostatic pressure of three times its rated pressure for 3 seconds without failure. The tire used to do the dynamometer qualification testing may be used if desired. e. Tire/Rim Slippage. Slippage of the tire on the rim during dynamometer testing must not damage the tube valve of tube type tires, or the gas seal of the tire bead of tubeless tires.

12. RETREAD TIRE DIMENSIONS. The tire dimensional envelope for a given tire size should be within industry accepted practices (e.g., TRA or ETRTO guidelines). When inflated to its rated inflation pressure and allowed to stretch for 12 hours, the tire should not exceed a “grown” tire dimensional envelope.

13. RETREAD BALANCE. All tires must be tested for static unbalance. a. Auxiliary Tires. (1) The moment of static unbalance (M) for auxiliary tires shall not be greater than the value determined by Eq. 1. Equation 1. M = 0.025 D0 2 (2) Computed Eq. 1 values must be rounded off to the next lower whole number where M is in inch/ounces and D0 is the standardized maximum outside diameter in inches. Tires outside the limits must be corrected for balance before entering service. b. Main Tires. (1) The moment of M for main tires shall not be greater than the value determined by Eq. 2. Equation 2. M = 0.035 D0 2 (2) Computed Eq. 2 values must be rounded off to the next lower whole number where M is in inch/ounces and D0 is the standardized maximum outside diameter in inches. Tires outside the limits must be corrected for balance before entering service.

14. INFLATION RETENTION. The pressure retention of the tire must be confirmed in accordance with TSO-C62.

15. RETREAD ESCALATION. a. The wide variation in tire operating environments, which affects the individual casing life, makes it inadvisable to arbitrarily specify the maximum number of times a tire should be retreaded. The number of times a tire can be retreaded should be controlled by an inspection and test system based on the retreader’s reliability program and the use of nondestructive interferometric (shearography) tire inspection. This procedure is applicable to both bias and radial ply tires. b. Following successful qualification of retreaded tires at the first retread level by size/ply rating/speed rating, and before entering into service tires of the first or subsequent R-levels, each part number should be escalated in accordance with the retread manufacturer’s escalation plan. Each plan should be submitted to and approved by the FAA.

16. RETREAD RELIABILITY SYSTEM. a. The Retread Reliability Program should monitor the in-service reliability of the retreaded aircraft tires. The reliability control system, to be consistent with the requirements of the aircraft it supports, should consist of a means to recognize a repetitive in-service issue, determine what plan of action would be needed to address this issue, and follow up on the action taken to remedy the issue. b. The corrective action taken depends on the results of the data collection and analysis. The corrective action should result in the identified tire issue being reduced within a reasonable timeframe.

Retreading is Recycling

A Special Report from Bridgestone Bandag Tire Solutions:

• Retreading is recycling. Retreading involves the re-use of most of the original tire “casing” and replaces the worn tread with a new tread, delivering the same balance of performance as the original product. Retreading a truck tire consumes significantly less oil to produce than a new tire, both in raw materials (many of which are made from oil derivatives) and energy consumed in the manufacturing process.

• It has been estimated that approximately 7 gallons of oil go into the material to retread a truck tire, as compared to the 22 gallons required to manufacture a new tire. The energy needed to retread a tire also has been estimated to require roughly 70% less energy than manufacturing a new one.

• Multiplying the 15 gallon savings per tire by the 13 million medium tires retreaded in 2009, equals a savings of over 195 million gallons of oil annually.

oil-barrels

• According to the U.S. Environmental Protection Agency, the United States generated approximately 290 million scrap tires in 2003. Over the years, more than 800 million scrap tires have accumulated in stockpiles.

• Also according to the EPA: “A tire’s physical structure, durability, and heat-retaining characteristics make these stockpiles a potential threat to human health and the environment. The curved shape of a tire allows rainwater to collect and creates an ideal habitat for rodents and mosquitoes. Prone to heat retention, tires in stockpiles also can ignite, creating fires that are difficult to extinguish and can burn for months, generating unhealthy smoke and toxic oils.”

• While there are more uses for scrap tires than ever before, the best way to deal with scrap tires is to avoid generating them – i.e., retread them. The EPA cites the following benefits of retreaded tires:

• Save resources by requiring 70 % less oil for production

• Contain 75 % post-consumer material

• Cost 30 to 70 % less than new tires

• Save landfill space

• The EPA also states that: “Retread tires not only offer considerable environmental and economic benefits, but they also provide quality, comfort, and safety comparable to that of new tires.”

• Considering that about 13 million medium truck tires are retreaded annually, and thus remain out of tire piles and landfills, retreads make a significant contribution to cleaning up the environment.

The Environmental Benefits of Tire Retreading

Millions of passenger, commercial truck and otr tire casings are retreaded each year, with total dollar savings in the billions and it’s good for the earth!

Retreading is used in many industries including trucking, mining, construction, shipping, cargo handling, air transportation and more. If you are buying or selling commercial tire casings, let CasingSource.com do the heavy lifting.