Bottom line
A tire changer demounts and mounts tires on rims. The manual kind is a steel post on a base plate with a bead-breaker arm and a long bar. A bead breaker pushes the tire's bead off its seat on the rim; a bead seater is an air tank that blasts it back on; bead sealer is a liquid; balancing beads are loose beads inside the tire. The drop center is the deep channel in the rim that makes mounting possible.
The words around tire changing are easy to mix up, because several of them sound alike and mean different things, and because some everyday names differ from the ones in manuals and tire-industry bulletins. This page lists the terms as this site uses them. Where a definition rests on a document, that document is in the sources at the end.
What is a tire changer?
A tire changer takes a tire off a rim and puts one on. Shops use powered machines for this. A manual tire changer does the same two jobs by hand: its lower arm breaks the bead, and a long bar levers the tire over the rim flange while the wheel is held on a center post. It has no motor and needs no air line. It also does not balance the wheel and does not inflate the tire; those are separate steps with separate tools, listed under tire changing tools.
Four bead words that are not the same thing
Most confusion comes from four terms that all contain the word bead.
- A bead breaker is a tool. It pushes the bead of the tire off its seat on the rim. The types are compared under tire bead breakers.
- A bead seater is an air tank. It blasts air between tire and rim to help the beads of a newly mounted tire move outward. See tire bead seaters.
- Bead sealer is a liquid for the contact area between bead and rim.
- Balancing beads are loose beads inside the tire. Here the word means small spheres, not the edge of the tire.
The bead itself, the part all of this is about, has its own page: what is a tire bead.
Rim words: flange, seat, hump, drop center
Seen in cross-section, a one-piece rim has a raised lip on each side, the rim flange. Inside each flange is a ledge, the bead seat, and next to it a low ridge, the safety hump. In the middle lies a deep channel, the drop center. The bead of a tire is smaller than the flange it has to cross, so it goes over only when the opposite side of the bead sits down in that channel. The drawing on the homepage shows all six parts, and the working steps that follow from it are under how to use a manual tire changer.
Duck head, mount head, bar tip
On a basic manual changer the tip of the steel bar runs along the rim edge. A mount/demount head, in everyday language a duck head, is a shaped head that takes over this job. Kits that add one to a manual changer are compared under duck-head tire changers. The head reduces contact between steel and rim. It does not change the size limits in the changer's manual.
Words used with care on this site
Three expressions have a narrower meaning here than in everyday use. “Test” appears only as a subject, because this site runs none; the method is described under how we research. “Fits” is used for size ranges a maker states in its own documents; a range that appears in a listing only is called a seller statement. And “seated” means that both beads sit evenly on their seats all the way around on both sides of the tire, checked by eye and not by a popping sound; the rule behind it is on the page how to seat a tire bead.
- Aspect ratio
- The height of a tire's sidewall as a percentage of its width; the second number of the tire size, for example 40 in 225/40R18. A low aspect ratio means a short, stiff sidewall. The tire makers ask for equipment designed for low aspect ratio tires.
- Balancing beads
- Loose beads placed inside a tire and sold as a balancing aid. They have nothing to do with the tire bead. The U.S. Tire Manufacturers Association states that it does not endorse any tire balancing product because it does not test them.
- Bead
- The stiff inner edge of a tire, built around a hoop of steel wire. It sits on the bead seat of the rim and seals the tire against it.
- Bead breaker
- A tool that pushes the bead off its seat and over the safety hump into the drop center. It is a separate hand tool or the lower arm of a manual tire changer. It does not take the tire off the rim.
- Bead lubricant
- A paste or liquid made for mounting tires, also called tire mounting lube or bead paste. The tire makers name commercially available bead lubricant first and rule out silicone, petroleum and solvent-based products.
- Bead sealer
- A liquid applied to the contact surfaces of bead and rim to help them seal. The tire makers warn that it can impede bead seating if it is allowed to dry on the contact surfaces before mounting.
- Bead seat
- The ledge of the rim on which the bead rests when the tire is inflated.
- Bead seater
- An air tank that releases a blast of air between tire and rim to push the beads toward their seats. Not to be confused with a bead breaker or bead sealer. The tire makers' limit of never more than 40 psi in the tire to seat beads applies with or without one.
- Bubble balancer
- A static wheel balancer: the wheel rests on a pivot, and a round spirit level shows the heavy side. It corrects imbalance in one plane and needs no power.
- Centering cone
- A cone that sits in the center hole of a wheel to center it on the post of a tire changer or on a balancer.
- Couple imbalance
- Uneven weight across the width of a wheel that cancels out at rest and makes the turning wheel wobble from side to side. It takes a spin balancer with two correction planes to find it.
- Drop center
- The deep channel in the middle of a one-piece rim, also called the well or drop well. The bead on the side opposite the tool has to sit in it; that gives the slack to get the bead over the rim flange.
- Duck head
- Everyday name for the mount/demount head of a tire machine, a shaped head that guides the bead over the rim flange. Sold as a kit for manual changers in place of the bare bar tip.
- Dynamic balancing
- Balancing a turning wheel in two planes, with weights on the inner and the outer side of the rim. It is what a spin balancer does.
- Floor-post changer
- This site's name for the common manual tire changer layout: a steel post on a base plate that is fixed to the floor, a bead-breaker arm near the base and a long bar.
- Flotation tire
- A wide type of tire that is named separately in the size limits of the reference manual changer: flotation tires up to size 12.5L16.
- LT tire
- A tire whose size designation carries the letters LT for light truck. The OSHA standard on servicing large-vehicle rim wheels does not apply to automobile tires or to truck tires designated LT.
- Manual tire changer
- A hand-operated tool that breaks the bead and levers a tire off and onto a one-piece rim without electric or pneumatic power.
- Mount/demount bar
- The long steel bar of a manual tire changer. One end levers the bead off the rim, the other works it back on; it also serves as the handle for the bead breaker.
- One-piece rim
- A rim made as a single part, as on cars, light trucks, motorcycles and most small equipment. Everything on this site concerns one-piece rims. Multi-piece truck rims have their own rules.
- Positive lock-down device
- The tire makers' term for a part of a tire machine that holds the wheel in place during inflation. If a machine has none, they call for a safety cage or other restraining device.
- Rim flange
- The raised outer lip of the rim. The bead has to be levered over it when a tire is mounted or demounted.
- Rim protector
- A plastic shield that is clipped over the rim flange under a tire iron. It reduces steel-on-rim contact; marks remain possible.
- Safety cage
- A cage that surrounds a wheel during inflation as a restraint in case the assembly bursts. The tire makers call for a cage or other restraining device when the machine cannot lock the wheel down.
- Safety hump
- A low ridge on the rim next to the bead seat that keeps the bead in place. Breaking the bead means pushing it over this hump.
- Snap-in valve
- The common rubber tubeless valve that is pulled into the valve hole of the rim. The tire makers say used snap-in valves are always replaced when tires are replaced.
- Static balancing
- Balancing in one plane, so that no side of the wheel is heavier than the side opposite. A bubble balancer does it with the wheel at rest.
- Tire iron, tire spoon, tire lever
- Hand levers for working a bead over the rim flange, used mainly on motorcycle and small tires. “Tire iron” is also a common name for the lug wrench, which is a different tool.
- TPMS
- Tire pressure monitoring system. Its sensor can sit at the valve, inside the tire. The tire makers recommend replacing the parts of the sensor's valve kit when a tire is replaced and following the vehicle maker's service requirements.
- Valve core
- The small spring-loaded insert inside the valve stem. Unscrewing it with a valve core tool is the sure way to empty a tire completely before the bead is broken.
Straight answers
What is a tire changer tool called?
The machine is called a tire changer or tire machine; the hand-operated kind is a manual tire changer. Its parts have names of their own: the bead breaker loosens the tire from the rim, the mount/demount bar levers it off and on, and a mount/demount head is often called a duck head. Hand levers used without a machine are tire irons or tire spoons.
What is the difference between a bead breaker and a bead seater?
They work in opposite directions. A bead breaker is used at the start of the job: it pushes the bead off its seat so the old tire can come off. A bead seater is used at the end: it is an air tank that blasts air between tire and rim so the beads of the new tire move toward their seats. Bead sealer, a liquid, is a third thing.
Is changing a tire the same as changing a wheel?
No. In this glossary, changing a tire means taking the tire off the rim and mounting another one. Swapping a flat for the spare at the roadside with jack and lug wrench is changing a wheel, even though it is commonly called changing a tire. A tire changer is for the first job only.
Paperwork: our sources
- U.S. Tire Manufacturers Association: Tire Information Service Bulletin Vol. 46, No. 4 (drop well, valves, TPMS, lock-down device, low aspect ratio tires)
- U.S. Tire Manufacturers Association: Tire Information Service Bulletin Vol. 41, No. 4 (bead lubricants, bead sealers, balancing substances)
- OSHA: 29 CFR 1910.177, Servicing multi-piece and single piece rim wheels (scope, LT designation)
- Harbor Freight: Pittsburgh Manual Tire Changer, item 58731 (product page: layout and size limits)
- U.S. Patent 4,015,481: Bubble balancer (principle of the bubble balancer)
- Coats: 1250 wheel balancer manual (static and dynamic balancing)
Next job
- ExplainerWhat is a tire bead?What a tire bead is, where it sits and how it works: the steel-wire edge of the tire, the bead seat, hump and drop center of the rim, and why it matters.
- Buying guideBead breakersClamp-type, slide-hammer and motorcycle bead breakers by tire type: ATV, lawn tractor, trailer, truck and motorcycle. Specs from the makers, limits included.
- Buying guideBead seatersWhat a tire bead seater does, what tank size and ASME compliance mean, which models publish their data, and why the 40 psi limit in the tire still applies.
- Buying guideDuck head kitsA duck head kit gives a manual tire changer a mount/demount head in place of the bare bar tip. Four kits compared by fit and post diameter, with the limits.
- Buying guideTire changing toolsThe tire changing tools a home garage needs to take a tire off a rim and mount a new one: changer, bead breaker, irons, lube, valves, air and balancer.
- How-toHow to use a changerHow to use a manual tire changer in 10 steps, taken from the owner's manual of the reference machine and the tire makers' bulletins, with the 40 psi limit.
Who is behind this page
manualtirechangers.com Editorial Team
Tire-changing tools, compared from the paperwork
We are the editorial team at manualtirechangers.com. We read owner's manuals, manufacturer specifications and tire-industry service bulletins, and turn them into plain buying advice and step-by-step guides for changing tires in a home garage.
- Owner's manuals & spec sheets read
- Safety rules from tire-industry sources
- Seller claims labeled as claims
- Compared by manufacturer data