Beadlock
Encyclopedia
A beadlock or bead lock is a mechanical device that secures the bead
of a tire
to the wheel
of a vehicle. Tires and wheels are designed so that, when the tire is inflated
, the tire pressure pushes the bead of the tire against the inside of the wheel rim
so that the tire stays on the wheel and the two rotate together. In situations where tire pressure is insufficient to hold the bead of the tire in place, a beadlock is needed.
There are several styles of beadlocks. For 4-wheel drive vehicles, a ring with a number of bolts around the circumference is used to clamp the tire to the wheel. For motorcycles, a rim lock or bead stopper is a curved plate tightened by a single bolt. For both 4-wheel drive vehicles and motorcycles, a different style of beadlock can be used that is similar to an inner tube which is inflated to press the tire against the wheel.
Bead lock may also refer to a product used to secure a swimming pool liner into the pool liner track installed on many above ground pools. It has a wedge shaped edge on the front of the strip. When installing the strip, it inserts just above the pool liner bead. It then locks the liner into the receiving track.
First manufactured for aftermarket racing and off road applications by Marsh Racing
Wheels at Siloam Springs, Arkansas
in 1980 but conceived, designed and tested by Marsh Racing Wheels years earlier.
High traction is desired for tires for automobile dirt track racing
, off-road racing
, off-road vehicles, and off-road motorcycles, so their tread is therefore coarse. Nevertheless, some riders will lower the tire pressure to cause the tread
to spread out and create a larger contact patch
. This practice can create a safety hazard, as there may not be enough pressure to adequately secure the tire beads to the wheel. Reactive ground forces push a tire to one side or the other, especially the outside rear tire of a racing vehicle when it is turning in a corner of a track. This could cause a bead of the tire to come off the rim completely, or enough to cause partial loss of air. It is also possible for the tire to have more traction on the ground than there is friction between the tire and rim. In this case the wheel would slip around the tire beads without turning the tire. Beadlocks, of one form or another including adhesive, are therefore used to keep the beads of off-road tires firmly seated and prevent slip, even when inflation pressure is low.
It is important to note that most standard beadlocks clamp only the outside bead. This is fine in most cases because the outside bead is the side that comes unseated most often while off-roading.
. The side of the beadlock closest to the tread, the "case", has a layer of thick fabric, generally polyester
, which keeps the beadlock from inflating too far up into the tire. This forces the sides into the tire which compresses the bead of the tire against the wheel.
stem attached to the plate is placed through a hole in the "well" of the rim, with the plate inside the tire and the threaded stem on the outside. The rim lock is tightened using either a standard bolt that leaves the threads visible, or a special bolt that covers the threads. The threaded stem or special bolt is visible on the inner surface of the wheel and points towards the axle, just like the valve stem
.
For motorcycle tires, a device similar to the internal beadlock of 4-wheel drive vehicles can be used. A special inner tube is inflated via its own valve stem to high pressure to push the bead of the tire tight against the wheel. Like the rim lock, this clamps both beads at once. The regular valve stem is used to inflate the tire to the desired pressure.
Tire bead
Tire bead is the term for the edge of a tire that sits on the wheel. Wheels for automobiles, bicycles, etc. are made with a small slot or groove for the tire bead to sit in. When the tire is properly inflated the air pressure within the tire keeps the bead in this groove...
of a tire
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
to the wheel
Wheel
A wheel is a device that allows heavy objects to be moved easily through rotating on an axle through its center, facilitating movement or transportation while supporting a load, or performing labor in machines. Common examples found in transport applications. A wheel, together with an axle,...
of a vehicle. Tires and wheels are designed so that, when the tire is inflated
Inflatable
An inflatable is an object that can be inflated with a gas, usually with air, but hydrogen, helium and nitrogen are also used. One of several advantages of an inflatable is that it can be stored in a small space when not inflated, since inflatables depend on the presence of a gas to maintain their...
, the tire pressure pushes the bead of the tire against the inside of the wheel rim
Rim (wheel)
The rim of a wheel is the outer circular design of the metal on which the inside edge of the tire is mounted on vehicles such as automobiles. For example, on a bicycle wheel the rim is a large hoop attached to the outer ends of the spokes of the wheel that holds the tire and tube.In the 1st...
so that the tire stays on the wheel and the two rotate together. In situations where tire pressure is insufficient to hold the bead of the tire in place, a beadlock is needed.
There are several styles of beadlocks. For 4-wheel drive vehicles, a ring with a number of bolts around the circumference is used to clamp the tire to the wheel. For motorcycles, a rim lock or bead stopper is a curved plate tightened by a single bolt. For both 4-wheel drive vehicles and motorcycles, a different style of beadlock can be used that is similar to an inner tube which is inflated to press the tire against the wheel.
Bead lock may also refer to a product used to secure a swimming pool liner into the pool liner track installed on many above ground pools. It has a wedge shaped edge on the front of the strip. When installing the strip, it inserts just above the pool liner bead. It then locks the liner into the receiving track.
History
Dodge Military trucks had the first beadlocks, called Combat Wheels; The 'combat wheels' were a divided-rim, that used a bolted-on retaining ring replacing the normal split ring wheels. They were designed for quick and easy tire replacement during combat, hence the name.First manufactured for aftermarket racing and off road applications by Marsh Racing
Marsh Racing
Marsh Racing is a team in the GRAND-AM Rolex Sports Car Series and formerly a team which competed in the NASCAR Busch Series. The team is owned by Ted Marsh. A longtime Chevrolet team sporting the No. 31 with backing from Whelen Engineering, Marsh Racing currently fields a Corvette in the Rolex...
Wheels at Siloam Springs, Arkansas
Siloam Springs, Arkansas
Siloam Springs is a city in Benton County, Arkansas, United States. According to 2005 Census Bureau estimates, the population of the city was 13,990...
in 1980 but conceived, designed and tested by Marsh Racing Wheels years earlier.
Purpose
Air pressure within a tire forces its beads against the wheel rim and normally ensures that the tire and rim rotate as a single unit. In general automotive situations, a tire's air pressure is sufficient to withstand dislodging and rim-slip forces experienced during, respectively, hard cornering and acceleration (including negative acceleration or "braking"). Low tire pressure therefore poses the hazard of enabling sudden loss of air, and loss of control, during hard braking or an evasive maneuver (in addition to generally promoting excessive tire heat and future failure). Modern automotive tires have a soft rubber formulation at the beads to help maintain good rim contact, so special bead-lock means are not required.High traction is desired for tires for automobile dirt track racing
Dirt track racing
Dirt track racing is a type of auto racing performed on oval tracks. It began in the United States before World War I and became widespread during the 1920s and 30s. Two different types of racecars predominated—open wheel racers in the Northeast and West and stock cars in the South...
, off-road racing
Off-road racing
Off-road racing is a format of racing where various classes of specially modified vehicles compete in races through off-road environments.-North America:...
, off-road vehicles, and off-road motorcycles, so their tread is therefore coarse. Nevertheless, some riders will lower the tire pressure to cause the tread
Tread
The tread of a tire or track refers to the rubber on its circumference that makes contact with the road. As tires are used, the tread is worn off, limiting its effectiveness in providing traction. A worn tire tread can often be retreaded. The word tread is often used incorrectly to refer to the...
to spread out and create a larger contact patch
Contact patch
Contact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is most commonly used in the discussion of pneumatic tires, , where the term is strictly used to describe the portion of the tire’s tread that touches the road surface...
. This practice can create a safety hazard, as there may not be enough pressure to adequately secure the tire beads to the wheel. Reactive ground forces push a tire to one side or the other, especially the outside rear tire of a racing vehicle when it is turning in a corner of a track. This could cause a bead of the tire to come off the rim completely, or enough to cause partial loss of air. It is also possible for the tire to have more traction on the ground than there is friction between the tire and rim. In this case the wheel would slip around the tire beads without turning the tire. Beadlocks, of one form or another including adhesive, are therefore used to keep the beads of off-road tires firmly seated and prevent slip, even when inflation pressure is low.
Standard beadlocks
A standard beadlock is designed to clamp the tire bead between an outer and an inner ring. The inner ring may be welded onto a standard wheel increasing wheel width by anywhere from 1½ to 2 inches or may be formed as part of the wheel when the wheel is made in the factory. The outer ring is then bolted onto the inner ring with the bead clamped between them. Anywhere between 16 and 32 bolts at around 10 ft·lbf are used around the circumference of the wheel to keep the clamp tight. The rings and bolts can cause problems with balancing the wheel and tire because all the added weight is on one side. This style is used exclusively for offroad use.It is important to note that most standard beadlocks clamp only the outside bead. This is fine in most cases because the outside bead is the side that comes unseated most often while off-roading.
Internal beadlocks
An internal beadlock is very much like an inner tube within the tire that pushes the bead of the tire tight against the wheel. The internal beadlock is inflated via its own valve stemValve stem
A valve stem is a self-contained valve which opens to admit gas to a chamber , and is then automatically closed and kept sealed by the pressure in the chamber, or a spring, or both, to prevent the gas from escaping...
. The side of the beadlock closest to the tread, the "case", has a layer of thick fabric, generally polyester
Polyester
Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
, which keeps the beadlock from inflating too far up into the tire. This forces the sides into the tire which compresses the bead of the tire against the wheel.
Streetlocks
Some people want their vehicle to look like it has beadlocks, but don't actually need the benefits of real beadlocks. Many wheels are therefore made to look like beadlocks but they don't actually lock anything. The off-road community generally refers to these as "streetlocks" since the owners typically don't use them for off road use. Streetlocks do improve the structural integrity of the wheel though, and are a good alternative in areas where beadlock wheels are not street legal.Motorcycle rim locks
Motorcycle tires use a different style of beadlock, also known as a rim lock or bead stopper. Motorcycle tire rim locks clamp both beads at once because the tire is narrow enough do this conveniently with one device, and also there is no such thing as an "inside bead" and "outside bead" on a motorcycle tire. A curved metal plate inside the tire presses both beads outward against the inside of the wheel rim to clamp both beads at once in one localized area. A threadedThreaded fastener
A threaded fastener is a discrete piece of hardware that has internal or external screw threads. They are usually used for the assembly of multiple parts and facilitate disassembly.The most common types are the screw and nut...
stem attached to the plate is placed through a hole in the "well" of the rim, with the plate inside the tire and the threaded stem on the outside. The rim lock is tightened using either a standard bolt that leaves the threads visible, or a special bolt that covers the threads. The threaded stem or special bolt is visible on the inner surface of the wheel and points towards the axle, just like the valve stem
Valve stem
A valve stem is a self-contained valve which opens to admit gas to a chamber , and is then automatically closed and kept sealed by the pressure in the chamber, or a spring, or both, to prevent the gas from escaping...
.
For motorcycle tires, a device similar to the internal beadlock of 4-wheel drive vehicles can be used. A special inner tube is inflated via its own valve stem to high pressure to push the bead of the tire tight against the wheel. Like the rim lock, this clamps both beads at once. The regular valve stem is used to inflate the tire to the desired pressure.