Buying aircraft wheels, brakes and tires: assembly, wear remaining, retread level, exchange and release paperwork

What you are buying: three different products

They are fitted together but bought as separate part numbers.

• Wheel assembly. Main wheels and nose wheels have different part numbers and are not interchangeable. The FAA's airframe handbook explains why the two halves of a main wheel are not identical either: the inboard half must accept and drive the brake rotors, through keys bolted or fitted to it. Both halves hold a bearing cup, and on high-performance wheels the inboard half carries thermal (fusible) plugs, whose core melts and lets the tire's pressure out before heavy braking can make the wheel burst. The halves are held together by tie bolts.
• Brake assembly. On airliners, a multiple-disc brake: a heat stack of rotors keyed to the wheel and stators keyed to the torque tube, pressed together by pistons. The heat stack is either steel, with friction linings, or carbon.
• Tire. A new tire or a retread, identified by size, ply rating, speed rating and the tire maker's part number, and approved under FAA TSO-C62.

Decide what you are asking for. "Wheel assembly" can mean a bare wheel or a wheel with a mounted tire; a wheel may be quoted with or without bearings. Say which on the RFQ.

Pin down the exact part

Start from the aircraft's IPC and the data plate of the removed unit: part number with dash number, serial number, and any modification marking. Some points specific to this category:

• Carbon or steel is a configuration, not a preference. Boeing's AERO magazine noted that carbon brakes were offered as an option for the 737 Next-Generation, with retrofit through service bulletins, and on other models through master change service bulletins. The brake your aircraft may use depends on its configuration and records, not on what is on the shelf. The wheel is often part of the same configuration, so check the IPC for both.
• Brake part numbers carry mod status. Ask which service bulletins are embodied, as you would for any rotable.
• Tires are specified by the tire maker's part number, plus size, ply rating and speed rating from the aircraft's approved data. The handbook notes that ply rating is now an index of strength, not a count of plies.

If you accept alternate part numbers, say which; see our interchangeability guide.

Brakes: wear remaining, carbon vs steel, and how they are supplied

How wear is measured, and how it is quoted

According to the FAA handbook, many brake assemblies have a built-in wear indicator pin: the exposed length shrinks as the linings wear, and a minimum length means the brake must be replaced. How the pin is measured varies from one brake to another, and the handbook says to consult the maker's data for each.

Quotes and listings often turn that measurement into a percentage: one line in our own quote data read simply "BRAKE ASSY; PIN LIFE: 96%". A percentage is a convenience, not a standard. Ask for:

• the measured pin length, the new length and the minimum from the CMM or maintenance manual, so you can check the percentage yourself;
• whether the figure refers to a brake just overhauled with a new or refurbished heat stack, or a used brake removed with wear left on it;
• for a used brake, the removal reason. A brake that has absorbed a rejected takeoff is a different unit from one removed at a scheduled wheel change.

Carbon and steel wear differently

Boeing's AERO article explains the difference. Steel brake wear is directly proportional to the kinetic energy the brake absorbs, so heavy weights and high speeds shorten its life. Carbon brake wear depends primarily on the total number of brake applications. The same article says carbon brakes offer up to twice as many landings per overhaul as steel, and that for most operations their life-cycle costs are now similar. For a buyer, the practical point is that the remaining life of a used carbon brake depends on how it will be used, so a percentage from one operator is not a forecast for another.

Outright, exchange or cost per landing

Brakes are commonly bought three ways:

• Outright: you buy the unit and own it.
• Exchange: you receive an overhauled brake now and send your worn one back as the core. The terms that decide the final bill, such as the core deadline, BER and over-and-above charges, are in our exchange guide.
• Service agreements: some airlines cover wheels and brakes under a long-term support contract instead of buying unit by unit. Brake economics are usually compared as a cost per landing; Boeing's AERO article, for one, compares carbon and steel brakes on that basis.

If your fleet is under such a contract, check before buying a brake elsewhere: an outside unit may not be something the contract accepts back.

Wheels: overhaul, inspections and small parts

A wheel is inspected and overhauled to its CMM. The FAA handbook lists the checks that matter most; ask about them on an overhauled wheel:

• Bead seat area: the critical, high-stress zone, where hard landings leave cracks that close up once the tire is off. Dye penetrant is generally ineffective there, and the handbook says eddy current inspection of the bead seat is required.
• Drive keys: cracks are common around them; dye penetrant is generally enough. The keys must be secure, within wear limits, with no corrosion in the area.
• Tie bolts: they stretch in service and crack at the threads and under the head; magnetic particle inspection finds them. A missing tie bolt means removal and full inspection of the wheel halves.
• Thermal plugs: inspected visually. If any core shows deformation from heat, all the plugs in the wheel are replaced. A plug that has released pressure means the wheel comes off for inspection.
• Bearings and cups: the cup must stay tight in the wheel: a cup that loosens and spins can damage the wheel. Corrosion beyond the manual's limits is cause to reject the wheel.

So for an OH wheel, ask for the shop's work order with the NDT results, and whether thermal plugs, bearings and tie bolts were replaced or reused. If you are sending your own wheel for overhaul instead of buying one, see repair or replace an aircraft component.

Tires: new, retread, and what is molded on the sidewall

Retreading, the FAA handbook says, reduces the effective cost of a tire over its life while the casing is sound. FAA AC 145-4A sets out how retreads are developed and approved, and what they must carry: the retreader's name, plant code, the month and year of the retread, and the letter R followed by the number of times the casing has been retreaded. The casing's own markings, including size, load rating, ply rating, speed rating, date of manufacture and serial number, must be restored if the retread removes them. The ply, load or speed rating may be reduced without approval, but any upgrade in speed or load rating counts as a new product.

How many retreads? The FAA handbook says no limit is set; it depends on the casing. A main gear tire may take "a handful" of retreads and some nose tires nearly a dozen, and retreads are not compromised in strength. Under AC 145-4A, each further R-level must meet escalation inspection and test criteria in the retreader's FAA-approved specification.

What about age? Goodyear's 2025 tire care manual says age is not an indicator of tire serviceability and that its tires have no expiration date as long as the service and visual criteria, or customer-imposed restrictions, are met. Storage still counts: the handbook asks for tires stored vertically on the tread, cool, dry and dark, away from ozone sources such as electric motors, and never stacked horizontally for more than six months. Ask how a stored tire was kept, and apply your own operator's limits.

Two more checks for an RFQ:

• R-level: if you accept retreads, say whether any R-level is acceptable or only up to a limit your operator sets.
• TSO revision: the FAA's tire maintenance AC (2018) references TSO-C62e. Goodyear's manual says tires qualified to earlier C62c and C62d revisions do not need requalification unless the tire is changed.

Goodyear's manual also says tires deflated by a fuse plug release should be scrapped. Ask whether a tire came off such a wheel.

Shipping a mounted tire: inflated or not

An inflated tire is a pressure vessel. Under US hazardous materials rules, 49 CFR 173.307 excepts tires inflated no higher than their rated pressure, but for air transport points to 49 CFR 175.8(b)(4): a tire assembly with a serviceable tire may travel if it is not inflated above its maximum rated pressure and the tire and valve are protected from damage. An unserviceable or damaged tire or assembly is forbidden from air transport unless it contains no hazardous material, such as a Division 2.2 compressed gas.

The IATA Dangerous Goods Regulations deal with tire assemblies in special provision A59, which since the 60th edition (2019) includes a maximum gauge pressure for the exception covering unserviceable or damaged assemblies. Check the current edition with your forwarder. Goodyear, for its part, notes that serviceable tires may be shipped fully pressurized but recommends reducing pressure to 25% of operating pressure or 3 bar (about 40 psi), whichever is less, and reinflating before fitting.

Put the inflation state on the RFQ and the PO. More on shipping regulated aircraft parts is in our dangerous goods guide.

Paperwork: what the release should show

For an overhauled wheel or brake released in the US, the usual document is FAA Form 8130-3; whether you need it, an EASA Form 1 or both is covered in 8130-3 vs EASA Form 1. Block 11 says what was done (overhauled, repaired, inspected/tested, modified), and block 12 can name the data used with its revision, SBs complied with, and replacement parts. For this category also ask for:

• for a brake: the measured wear pin length, and whether the heat stack is new or refurbished;
• for a wheel: the NDT results and what was replaced (plugs, bearings, tie bolts);
• for a tire: the R-level and retread date on the sidewall, matching the paperwork;
• for a used unit: the removal reason and a non-incident statement.

Check the condition codes behind the release in our condition codes guide.

Checklist: what to ask before the PO

If the RFQ comes to us, each line comes back with condition, certificates, lead time in days, minimum order and, where the supplier states it, the ships-from country. When you order in our client portal, you can tick "certificate needed" per line and add a note, which is where the wear pin, R-level and inflation questions above belong.

Sources

All checked on 24 September 2026.

• FAA-H-8083-31B, Aviation Maintenance Technician Handbook – Airframe, Chapter 13, Aircraft Landing Gear Systems — Federal Aviation Administration (wheel halves, thermal plugs, bead seat eddy current, drive keys, tie bolts, bearings, wear indicator pins, carbon brakes, tire nomenclature, ply rating, retreading, storage).
• AC 145-4A, Inspection, Retread, Repair, and Alterations of Aircraft Tires, Change 2 (29 November 2018), paragraphs 6, 9, 10 and 17 — Federal Aviation Administration.
• AC 20-97B, Aircraft Tire Maintenance and Operational Practices, Change 1 (11 September 2018) — Federal Aviation Administration (TSO-C62e reference).
• Operational Advantages of Carbon Brakes — Tim Allen, Trent Miller and Evan Preston, Boeing AERO, Q3 2009 (archived copy).
• Aircraft Tire Care & Maintenance, revised April 2025 — Goodyear Aviation (retread markings, TSO-C62e requalification, age, mounted assembly storage, shipping inflation, fuse plug release).
• 49 CFR 175.8(b)(4) and 49 CFR 173.307(a)(2) — eCFR.
• Significant changes and amendments to the 60th edition (2019) of the IATA Dangerous Goods Regulations — revision to special provision A59 (DGI training summary of the IATA list).
• MG AVIATION TECH supplier quote data, June – September 2026 (snapshot of 24 September 2026): shares of condition, stated certificate and stated trace on wheel, brake and tire quote lines, and the count of distinct part numbers; category by line description.