Beadlock
From Wikipedia, the free encyclopedia
A beadlock is a mechanical device that secures the bead of a tire to the wheel.--- First manufactured by Marsh Racing Wheels at Siloam Springs, Arkansas in 1980 but conceived designed and tested by Marsh Racing Wheels years earlier.[citation needed]
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[edit] Purpose
Air pressure within a tire forces its bead against the wheel rim and ensures that they rotate as a single unit. More traction is needed for tires on a dirt track racing or off-road vehicle. Drivers will often lower the air 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 secure the tire to the wheel. There are situations where there is a lot of pressure pushes the tire to one side or the other, especially on the outside rear tire of a dirt track racing vehicle when it is turning in a corner of an oval. This causes the bead of the tire to come off the wheel. It is also possible for the tire to have more traction on the ground than there is friction between the tire and wheel. In this case the wheel would spin within the tire without being able to turn the tire. Beadlocks are therefore designed to "lock" the bead of the tire onto the wheel.
[edit] 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 1 1/2 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.
 A standard beadlock with tire mounted and bolts tightened. |
 The same wheel with the tire, bolts, and outer ring removed. |
[edit] 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 stem. 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.
 Cut away view of internal beadlocks within tires. |
 Cross-section view of internal beadlocks. |
[edit] 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 for states where beadlock wheels are not street legal.
