Airless tire

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

The main advantages of airless tires is that they do not go flat and need to be replaced less frequently. Heavy equipment outfitted with airless tires will be able to carry more weight and engage in more rugged activities.

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; any airless tire will be heavier than the rubber tire it is meant to replace.

However, airless tires are not popular with hardcore off-roaders, as those vehicles often need to travel long distances at highway speeds. At speeds above 80 km/h, they can be unstable, causing severe vibrations (and passenger discomfort), and therefore potential for drivers to lose vehicle control.

Installation of airless tires depends on the use. Heavy machines using airless tires will need specialized tools to mount, whereas a flat-free bicycle tire can be mounted with little effort. Solid airless lawnmower tires come pre-installed on the wheel, allowing quick installation.^{[citation needed]}

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