How do smaller gaps between tread cause a regular tire in the mud to resemble a slick tyre?
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Paddle tire Paddle tires are mainly used on off road vehicles, specifically designed for use in sand and mud. They consist of a smooth tire core which has a series of large rubber cups (or paddles) attached to it. The volume inside of a paddle is much larger than the void of a knobby tire, so it is unlikely to clog up with sand/mud. A street legal mud tire is a more or less normal tire, but with extra large gaps or "voids" between each tread block (called "lugs") to allow centrifugal force to "self-clean" or fling the mud out of the gap. Smaller gaps trap the mud in between the tire lugs, which turns the tire into something resembling a "slick" with no tread at all, which will have no traction in mud. A paddle tire is an even more extreme version of this, optimized for mud or sand. The paddle provides superior traction in the sand, in part, because the paddles dig into the sand and push off from the buried sand, not just the surface, and in mud, the gigantic "voids" give no place for mud to stick. They work something like a paddle wheel on a paddle-steamer. Street legal mud tires are a compromise between large voids and a smooth rolling shape for on-road use. The more "extreme" a mud tire (such as a "Super Swamper") is, the harsher and louder it is on a hard surface. A "tractor tire" on a farm tractor is a somewhat more mild version of a paddle tire, only the voids are smaller to allow for limited use on hard surfaces, and the "lugs" are angled to give lateral traction. A paddle tire is so optimized for mud that the shape is of no use on anything other than a soft surface, since the vibration and lack of control of the tire would render a vehicle almost unusable. One other way the paddle tire is a specialized-application-only is that it gives only forward/rearward traction. This means that it is used on a wheel that drives a vehicle to push it forward, but gives little "lateral" (side-to-side) traction. For that reason, the tires of the vehicle that steer it are generally more "normal" tires, since a paddle tire on a steering wheel will just slide sideways rather than pulling the vehicle with it. So many 4WD vehicles will use paddle tires only on the rear, although the front wheels are powered as well. On a 2WD or a motorbike, the rear wheel is the only drive wheel, and so putting a paddle tire on the front wheels is useless or worse, since steering performance will be negatively impacted.
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Racing slick A racing slick (also known as a "slick tyre") is a type of tyre that has a smooth tread used mostly in auto racing. The first production "slick tyre" was developed by M&H Tires in the early 1950s for use in drag racing. By eliminating any grooves cut into the tread, such tyres provide the largest possible contact patch to the road, and maximize traction for any given tyre dimension. Slick tyres are used on road or oval track racing, where steering and braking require maximum traction from each wheel, but are typically used on only the driven (powered) wheels in drag racing, where the only concern is maximum traction to put power to the ground.
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Slope stability Slope stability is the potential of soil covered slopes to withstand and undergo movement. Stability is determined by the balance of shear stress and shear strength. A previously stable slope may be initially affected by preparatory factors, making the slope conditionally unstable. Triggering factors of a slope failure can be climatic events which can then make a slope unstable, leading to mass movements. Mass movements can be caused by increase in shear stress, such as loading, lateral pressure, and transient forces. Alternatively, shear strength may be decreased by weathering, changes in pore water pressure, and organic material.
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Mudcrete Mudcrete is a structural material (employed, for example, as a basecourse in road construction) made by mixing mud (usually marine mud) with sand and concrete/cement. It is used as a cheaper and more sustainable alternative to rock fill. It is also used in such projects as land reclamation.
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Continental tire A Continental tire is an upright, external, mounted spare tire behind an automobile's trunk compartment. The term also describes a non-functional bulge that is stamped into the trunk lid or a cosmetic accessory to the rear of the car giving the impression of a spare tire mount.
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Slush Slush, also called slush ice, is a slurry mixture of small ice crystals (e.g., snow) and liquid water. In the natural environment, slush forms when ice or snow melts. This often mixes with dirt and other materials, resulting in a gray or muddy brown color. Often, solid ice or snow will block the drainage of fluid water from slushy areas, so slush often goes through multiple freeze/thaw cycles before completely disappearing. In areas where road salt is used to clear roadways, slush forms at lower temperatures than it would ordinarily, and only in salted areas; this can produce a number of different consistencies over the same geographical area.
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Shadow blister effect The shadow blister effect is a visual effect whereby adjacent shadows appear to bulge (or blister) towards one another when cast by one or more non-point light sources. It is the result of overlapping shadow penumbra on the surface and the perception by the brain of a contrast barrier formed by the merging of the penumbra. The visual effect is proportionate to the distance of the obstructions to the shadow surface (as the penumbras become larger), as well as the angular diameter of the light source(s). Penumbras can be easily demonstrated using Ray Theory.
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Ripple marks In geology, ripple marks are sedimentary structures (i.e. bedforms of the lower flow regime) and indicate agitation by water (current or waves) or wind.
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Underseal Underseal (often called undercoating in the U.S.) is a thick resilient coating applied to the underbody or chassis of an automobile to protect against impact damage from small stones, which would rapidly chip ordinary paint, allowing rusting to begin.
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Saltation (geology) In geology, saltation (from Latin "saltus", "leap") is a specific type of particle transport by fluids such as wind or water. It occurs when loose material is removed from a bed and carried by the fluid, before being transported back to the surface. Examples include pebble transport by rivers, sand drift over desert surfaces, soil blowing over fields, and snow drift over smooth surfaces such as those in the Arctic or Canadian Prairies.
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Pseudofossil Pseudofossils are inorganic objects, markings, or impressions that might be mistaken for fossils. Pseudofossils may be misleading, as some types of mineral deposits can mimic lifeforms by forming what appear to be highly detailed or organized structures. One common example is when manganese oxides crystallize with a characteristic treelike or dendritic pattern along a rock fracture. The formation of frost dendrites on a window is another common example of this crystal growth. Concretions are sometimes thought to be fossils, and occasionally one contains a fossil, but are generally not fossils themselves. Chert or flint nodules in limestone can often take forms that resemble fossils.
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Pseudotachylite Pseudotachylite or Pseudotachylyte (original spelling) is a cohesive glassy or very fine-grained rock that occurs as veins and often contains inclusions of wall-rock fragments. Pseudotachylite is typically dark in color; and is glassy in appearance. It was named after its appearance resembling the basaltic glass, tachylyte. Typically, the glass is completely devitrified into very fine-grained material with radial and concentric clusters of crystals. The glass may also contain crystals with quench textures that formed via crystallization from the melt. Chemical composition of pseudotachylyte generally reflects the local bulk chemistry. Pseudotachylyte may form via frictional melting of faults, in large-scale landslides, and by impact processes. Many researchers often define the rock as one formed via the melting (c.f. fault rock). However, the original description/definition by Shand did not include interpretation about its generation, and it is suggested that there are pseudotachylytes formed via comminution without melting (e.g. Wenk, 1978).
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Pellets (petrology) Pellets are small spherical to ovoid or rod-shaped grains that are common component of many limestones. They are typically 0.03 to 0.3 mm long and composed of carbonate mud (micrite). Their most common size is 0.04 to 0.08 mm. Pellets typically lack any internal structure and are remarkably uniform in size and shape in any single limestone sample. They consist either of aggregated carbonate mud, precipitated calcium carbonate, or a mixture of both. They either are or were composed either of aragonite, calcite, or a mixture of both. Also, pellets composed of either glauconite or phosphorite are common in marine sedimentary rocks. Pellets occur in Precambrian through Phanerozoic strata. They are an important component mainly in Phanerozoic strata. The consensus among sedimentologists and petrographers is that pellets are the fecal products of invertebrate organisms because of their constant size, shape, and extra-high content of organic matter.
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Voids in mineral aggregate Voids in Mineral Aggregate or VMA is the intergranular space occupied by asphalt and air in a compacted asphalt mixture. In a component diagram, it is the sum of the volume of air and the volume of effective asphalt. The volume of absorbed asphalt is not considered to be a part of VMA because it is part of the pore structure of the mineral aggregate.
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Cirrocumulus cloud Cirrocumulus is one of the three main genus-types of high-altitude tropospheric clouds, the other two being cirrus and cirrostratus. They usually occur at an altitude of 5 km to 12 km . Like lower altitude cumuliform and stratocumuliform clouds, cirrocumulus signifies convection. Unlike other high cirrus and cirrostratus, cirrocumulus includes a small amount of liquid water droplets, although these are in a supercooled state. Ice crystals are the predominant component, and typically, the ice crystals cause the supercooled water drops in the cloud to rapidly freeze, transforming the cirrocumulus into cirrostratus. This process can also produce precipitation in the form of a virga consisting of ice or snow. Thus cirrocumulus clouds are usually short-lived. They usually only form as part of a short-lived transitional phase within an area of cirrus clouds and can also form briefly as a result of the breaking up of part of a cumulonimbus anvil.
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Crevasse splay A crevasse splay is a sedimentary fluvial deposit which forms when a stream breaks its natural or artificial levees and deposits sediment on a floodplain. A breach that forms a crevasse splay deposits sediments in similar pattern to an alluvial fan deposit. Once the levee has been breached the water flows out of its channel. As the water spreads onto the flood plain sediments will start to fall out of suspension as the water loses energy. The resulting deposition can create graded deposits similar to those found in Bouma sequences. In some cases crevasse splays can cause a river to abandon its old river channel, a process known as avulsion. Breaches that form a crevasse splay deposits occur most commonly on the outside banks of meanders where the water has the highest energy. Crevasse splay deposits can range in size. Larger deposits can be 6 m thick at the levee and spread 2 km wide, while smaller deposits may only be 1 cm thick.
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Snow chains Snow chains, or tire chains, are devices fitted to the tires of vehicles to provide maximum traction when driving through snow and ice.
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Soft-sediment deformation structures Soft-sediment deformation structures develop at deposition or shortly after, during the first stages of the sediment's consolidation. This is because the sediments need to be "liquid-like" or unsolidified for the deformation to occur. These formations have also been put into a category called water-escape structures by Lowe (1975). The most common places for soft-sediment deformations to materialize are in deep water basins with turbidity currents, rivers, deltas, and shallow-marine areas with storm impacted conditions. This is because these environments have high deposition rates, which allows the sediments to pack loosely.
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Road surface A road surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, cobblestone and granite setts were extensively used, but these surfaces have mostly been replaced by asphalt or concrete laid on a compacted base course. Road surfaces are frequently marked to guide traffic. Today, permeable paving methods are beginning to be used for low-impact roadways and walkways.
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Peniche (fluid dynamics) A peniche (or stand-off) is material inserted between a half-model, often of an airplane, and the wall of a wind tunnel. "Péniche" is a French nautical term meaning barge. The purpose of the peniche is to remove or reduce the influence of the boundary layer on the half-model. The effect of the peniche itself in fluid dynamics is not fully understood.
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Skid mark A skid mark is the visible mark left by any solid which moves against another, and is an important aspect of trace evidence analysis in forensic science and forensic engineering. Skid marks caused by tires on roads occur when a vehicle wheel stops rolling and slides or spins on the surface of the road. Skid marks can be analyzed to find the maximum and minimum vehicle speed prior to an impact or incident. Skidding can also occur on black ice or diesel deposits on the road and may not leave a mark at all.
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Cold inflation pressure Cold inflation pressure is the inflation pressure of tires before the car is driven and the tires warmed up. Recommended cold inflation pressure is displayed on the owner's manual and on the placard (or sticker) attached to the vehicle door edge, pillar, glovebox door or fuel filler flap. Drivers are encouraged to make sure their tires are adequately inflated, as suboptimal tire pressure can greatly reduce fuel economy, increase emissions, increased wear on the edges of the tire surface, and can lead to premature failure of the tire. Excessive pressure, on the other hand, may lead to impact-breaks, decrease braking performance, and cause uneven wear (i.e. greater wear on the center part of the tire surface).