Airless tire

Airless tires, or non-pneumatic tires (NPT), are tires that are not supported by air pressure. They are used on some small vehicles such as riding lawn mowers and motorized golf carts. They are also used on heavy equipment such as backhoes, which are required to operate on sites such as building demolition, where risk of tire punctures is high. Tires composed of closed-cell polyurethane foam are also made for bicycles and wheelchairs.

 

12-16.5 Mk1 Croc Tyre with rim center fitted

Advantages

The main advantage of airless tires is that they cannot go flat. Other advantages are that airless tires will need to be replaced less often resulting in a savings. Heavy equipment outfitted with airless tires will be able to carry more weight and engage in more rugged activities. Airless bicycle tires can be easy to install. Airless lawn mower tires come in several varieties.

Disadvantages

Airless tires generally have higher rolling resistance and provide somewhat less suspension than similarly shaped and sized pneumatic tires. Other problems for airless heavy equipment tires include dissipating the heat buildup that occurs when they are driven. Airless tires are often filled with compressed polymers (plastic), rather than air or can be a solid molded product.

Airless tires are attractive to cyclists, as bicycle tires are much more vulnerable to punctures than motor vehicle tires. The drawbacks to airless tires depend on the use. Heavy equipment operators who use machinery with solid tires will complain of fatigue whereas lawn mowers that use solid or airless tires have no drawbacks. Bicycle riders who use airless tires may complain that the tire is harder than a comparable pneumatic tire. Only anecdotal evidence exists that airless tires may cause broken spokes on a bicycle wheel. Any airless tire will be heavier than the rubber tire it is meant to replace; however, many rubber pneumatic tires are also heavy. Rubber tires vary in rolling resistance and an airless tire or solid insert may only marginally increase rolling resistance if at all.

Installation of airless tires depends on the use. Heavy equipment will need special equipment to mount but an airless bicycle tire can be mounted with little or no effort. Solid airless lawnmower tires come pre-installed on the wheel allowing quick installation.

Examples

Mobike tire

Many bicycle-sharing systems use these tires to reduce maintenance.

In 2005, Michelin started developing an integrated tire and wheel combination, the “Tweel” (derived from “tire” and “wheel,” which, as the name “Tweel” suggests, are combined into one new, fused part), which operates entirely without air. Michelin claims its “Tweel” has load carrying, shock absorbing, and handling characteristics that compare favorably to conventional pneumatic tires.[1] However, the tire has a lot of vibration when driving over 80 km/h (50 mph). A market roll out is therefore not planned in the near future. The automotive engineering group of the mechanical engineering department at Clemson University is developing a low energy loss airless tire with Michelin through the NIST ATP project.

Crocodile Tyres developed and sells a robust version that bolts to standard mining equipment.[2]

Resilient Technologies and the University of Wisconsin–Madison’s Polymer Engineering Center are creating a “non-pneumatic tire”, which is basically a round polymeric honeycomb wrapped with a thick, black tread. The initial version of the tire is for the Humvee and is expected to be available in 2012.[3][4] Resilient Technologies airless tires have been tested and are used by the U.S. Army.[5] and is also the first group to make a commercially available mass-produced airless tire after their acquisition by Polaris,[6] albeit, only as coupled with their vehicle. The tire trade mark is “Terrainarmor”

Bridgestone is developing the Bridgestone Air-Free Concept Tire,[7] which is similar to the Tweel, and can hold 150 kg (330 lb) per tire.[8]

The Energy return wheel has the outer edge of the tire connected to the inner rim by a system of springs. The springs can have their tension changed to vary the handling characteristics.[9]

Big Tyre Pty Ltd in Australia is developing a “non-pneumatic, non-solid wheel”, which is designed to handle high working loads, such as those found in underground mines. The wheel utilizes multiple arrays of concentric leaf springs[10] to distribute force evenly across the wheel. A prototype of the wheel was built in 2011,[11] and has been tested on an Eimco 936underground loader.[12]

In 1938, J. V. Martin in the United States invented a safety tire with hoops of hickory encased in rubber and fitted with crisscross spokes of ribbed rubber. It could drive over 100 mm (4 inches) blocks when tested in a springless test car.[13]

Hankook Tire is developing the iFlex airless tire.[14][15]

References

  1. Mihalascu, Daniel (2010-04-30). “Reinventing the Wheel: a Guide to Michelin’s Airless Tire”. Retrieved 2015-12-31.
  2. “Technology”. Australia: Crocodile Tyres. Retrieved 2016-10-02.
  3. Rutherford, Mark (2008-11-17). “New honeycomb tire is ‘bulletproof'”. CNET. Retrieved 2008-11-23.
  4. Youtube video. Retrieved 2011-12-27.
  5. “Non-Pneumatic Tire (NPT) – For Military and Commercial Applications” (Press release). Resilient Technologies. 2011. Retrieved 2012-09-22.
  6. Edelstein, Stephen (2013-11-18). “Polaris Airless Tires Go On Sale”. Motor Authority. Retrieved 2015-02-15.
  7. “Bridgestone Corporation Reveals Second Generation “Air Free Concept (Non-Pneumatic) Tire”” (Press release). Bridgestone. 2013-11-21. Retrieved 2015-10-20.
  8.  Boyer, Mark (2011-12-31). “Bridgestone Air-Free Concept Tyre”. inhabit.com. Retrieved 2012-04-19.
  9.  Michler, Andrew (2011-12-28). “Airless, Springy ‘Energy Return Wheel’ Tire Promises To Improve Gas Mileage”. inhabit.com. Retrieved 2012-04-19.
  10.  “Diagram and Patent Details of Big Tyre’s Non-pneumatic, Non-solid Wheel” (Press release). Big Tyre. Archived from the original on 2013-12-29. Retrieved 2013-11-01.
  11.  “Non-pneumatic, Non-solid Wheel for Underground Mining” (Press release). Big Tyre. Retrieved 2013-01-11.
  12.  “Youtube video – Non-pneumatic, Non-solid Wheel on an Eimco 936 Underground Loader”. Retrieved 2013-11-01.
  13.  “Rubber Spokes Give Bounce to Airless Safety Tires”. Popular Science. May 1938. Retrieved 2015-10-20.
  14.  Collie, Scott (2015-07-16). “Hankook’s high-speed tests inch airless tires closer to production”. GizMag. US. Retrieved 2016-10-02.
  15.  “Hankook Tire’s Future-oriented Tire Succeeds High-speed Driving without Air Pressure”(Press release). Korea: Hankook Tire. 2015-07-14. Retrieved 2016-10-02.
Tread The tread of a tire or track refers to the rubber on its circumference that makes contact with the road or the ground. As tires are used, the tread is worn off, limiting its effectiveness in providing traction. A worn tire can often be retreaded. The word tread is often used casually to refer to the pattern of grooves molded into the rubber, but those grooves are correctly called the tread pattern, or simply the pattern. The grooves are not the tread, they are in the tread. This distinction is especially significant in the case of racing slicks, which have a lot of tread but no grooves. Tires Common tire tread pattern. Street tires The grooves in the rubber are designed to allow water to be expelled from beneath the tire and prevent hydroplaning. The proportion of rubber to air space on the road surface directly affects its traction. Design of tire tread has an effect upon noise generated, especially at freeway speeds. Generally there is a tradeoff of tre...
Direct TPMS Direct TPMS, or direct tire pressure monitoring systems (direct sensor TPMS) refers to the use of a pressure sensor directly mounted on the wheels or tires of a vehicle. The pressure inside the tire is measured using a pressure transducer with the pressure information being subsequently sent to the vehicle to warn the driver of under or over inflation of a tire. The pressure information is commonly transmitted to the vehicle using radio frequency (RF) technology, though systems using mechanical, electrical or magnetic methods have been used over recent years. Typical system direct TPM sensor fitted in valve system, manufacturer VDO In most current designs of direct TPMS, a small electronic assembly which is rugged enough to be mounted inside a tire, measures the pressure using a microelectromechanical system (MEMS) pressure sensor and then transmits this and other information to one or more vehicle receivers. Other information can include a serial number, tempera...
Run-flat tire A run-flat tire is a pneumatic vehicle tire that is designed to resist the effects of deflation when punctured, and to enable the vehicle to continue to be driven at reduced speeds - under 56 mph (90 km/h) - and for limited distances - generally between 10 mi (16 km) to 50 mi (80 km), depending on the type of tire. Cutaway model of MOWAG Piranha tire Technologies There are three basic technologies currently available, described below. Self-supporting The origins of the commercial self-supporting run-flat tire started in 1935 with a tire that had a fabric inner tire. The tire was advertised as a protection against blow outs, a common and dangerous occurrence in the 1930s. In 1934, Michelin introduced a tire that was based on technology developed for local commuter trains and trolleys. It had a safety rim inside the tire which if punctured would run on a special foam lining. The tire was sold for military use and for specialized vehicles like bank armoured cars. It was adve...
Central tire inflation system A central tire inflation system (CTIS) is a system to provide control over the air pressure in each tire of a vehicle as a way to improve performance on different surfaces. For example, lowering the air pressure in a tire creates a larger area of contact between the tire and the ground and makes driving on softer ground much easier. It also does less damage to the surface. This is important on work sites and in agricultural fields. By giving the driver direct control over the air pressure in each tire, maneuverability is greatly improved. Another function of the CTIS is to maintain pressure in the tires if there is a slow leak or puncture. In this case, the system controls inflation automatically based on the selected pressure the driver has set. Tractor-drawn trailer with CTIS Tatra T813 prototype had CTIS already in 1960, it later became standard for all Tatra military trucks CTIS is extensively used in many off-road transport operations....
Tire manufacturing Pneumatic tires are manufactured according to relatively standardized processes and machinery, in around 455 tire factories in the world. With over 1 billion tires manufactured worldwide annually, the tire industry is the major consumer of natural rubber. Tire factories start with bulk raw materials such as synthetic rubber (60% -70% of total rubber in the tire industry), carbon black, and chemicals and produce numerous specialized components that are assembled and cured. This article describes the components assembled to make a tire, the various materials used, the manufacturing processes and machinery, and the overall business model. The tire is an assembly of numerous components that are built up on a drum and then cured in a press under heat and pressure. Heat facilitates a polymerization reaction that crosslinks rubber monomers to create long elastic. Inner liner The inner liner is an extruded halobutyl rubber sheet compounded with additives that result in low air perme...