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Tire rotation is the practice of moving the wheels and tires of an automobile from one position to another, to ensure even tire wear. Even tire wear extends the useful life of a set of tires, but the value of this is disputed.
The differing weight placed on the tires by the front and rear axles causes uneven wear. With the majority of cars having the engine in front, the front tires typically bear more weight than the rear tires. Front-wheel drive vehicles have not only the engine but also the transaxle in front, adding to the weight difference. Moreover, additional stress is placed disproportionately on the front tires by braking and steering. Thus, tire rotation needs to occur more frequently for front-wheel drive vehicles.
Turning the vehicle will cause uneven tire wear. The outside, front tire is worn disproportionately. [1] In countries with right-hand traffic, for example, right turns are tighter than left turns and most cloverleaf interchanges and parking ramps are right-hand curves, so the left front tire wears faster than the right front, because the left tire travels a greater distance around those turns (the same way that an athlete in the leftmost lane would have to run further around an oval track than one in the rightmost if the race were being run clockwise from a flat line start) and a majority of turns will be to the right. [2] Conversely, the sidewalls on the right tire tends to be bumped and rubbed against the curb while parking the vehicle, causing asymmetric sidewall wear. The symmetric opposite occurs in countries that drive on the left.
In addition, mechanical problems in the vehicle may cause uneven tire wear. Wheels misaligned with each other and/or with the vehicle's axis will tend to be dragged along by the other wheels, causing uneven wear in that tire. If the alignment is such that the vehicle tends to turn, the driver will correct by steering against the tendency. In effect the vehicle is constantly turning, causing uneven tire wear.
Car and tire manufacturers may recommend tire rotation frequency and pattern, typically every 5,000 mi (≈8,000 km) to 8,000 mi (≈13,000 km) depending on the tire manufacturer and vehicle make [3] to ensure even tire wear.
A common rotation pattern is to move the back wheels to the front, and the front to the back but crossing them when moving to the back.[ citation needed ] If the tires are unidirectional, the rotation can only be rotated front to back on the same side of the vehicle to preserve the rotational direction of the tires, unless they are remounted.
More complex rotation patterns are required if the vehicle has a full-size spare tire that is part of the rotation, or if there are snow tires.
The benefits of achieving even tire wear, using rotation, are disputed. Some car manufacturers recommend against performing tire rotation, for example BMW. [4] Many tire manufacturers say that tire rotation is no longer necessary, except to ensure that best tires are fitted at the rear of the vehicle. [5] In practice this means that when the front tires become worn, the new ones should be fitted to the rear, moving the old rear tires to the front.
Maximum vehicle control is achieved with the best tires on the rear wheels of the vehicle, whether it is front- or rear-wheel drive. [6] The reason for this is that if the rear wheels lose grip before the front ones, an oversteer condition will occur, which is harder to control than the corresponding understeer which will happen if a front wheel is lost. So the intuitive belief that the front steering/driving tires need to be the best quality is not the case. [7]
This is also the case if a tire blows out. A rear tire blowout will cause the vehicle to become very difficult to control, especially at highway speeds. It also greatly increases the risk of rollover due to yawing, a condition where the rear of the vehicle swings out and becomes perpendicular to the direction of travel: yawing can cause the tire to separate from the rim, leading the rim to dig into the pavement, or dirt and grass if no longer on the road, which can trip the vehicle and cause its rollover.[ citation needed ]
A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, which also provide a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, that is designed to match the weight of the vehicle with the bearing strength of the surface that it rolls over by providing a bearing pressure that will not deform the surface excessively.
An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type of axle is referred to as a spindle.
A skid loader, skid-steer loader, SSL, or skidsteer is any of a class of compact heavy equipment with lift arms that can attach to a wide variety of buckets and other labor-saving tools or attachments.
Steering is a system of components, linkages, and other parts that allows a driver to control the direction of a vehicle.
Automobile handling and vehicle handling are descriptions of the way a wheeled vehicle responds and reacts to the inputs of a driver, as well as how it moves along a track or road. It is commonly judged by how a vehicle performs particularly during cornering, acceleration, and braking as well as on the vehicle's directional stability when moving in steady state condition.
In automotive design, a front-engine, front-wheel-drive (FWD) layout, or FF layout, places both the internal combustion engine and driven roadwheels at the front of the vehicle.
In automotive design, an RR, or rear-engine, rear-wheel-drive layout places both the engine and drive wheels at the rear of the vehicle. In contrast to the RMR layout, the center of mass of the engine is between the rear axle and the rear bumper. Although very common in transit buses and coaches due to the elimination of the drive shaft with low-floor buses, this layout has become increasingly rare in passenger cars.
A caster is an undriven wheel that is designed to be attached to the bottom of a larger object to enable that object to be moved.
A locking differential is a mechanical component, commonly used in vehicles, designed to overcome the chief limitation of a standard open differential by essentially "locking" both wheels on an axle together as if on a common shaft. This forces both wheels to turn in unison, regardless of the traction available to either wheel individually.
The wheel size for a motor vehicle or similar wheel has a number of parameters.
Weight transfer and load transfer are two expressions used somewhat confusingly to describe two distinct effects:
Electronic brakeforce distribution or electronic brakeforce limitation (EBL) is an automobile brake technology that automatically varies the amount of force applied to each of a vehicle's wheels, based on road conditions, speed, loading, etc, thus providing intelligent control of both brake balance and overall brake force. Always coupled with anti-lock braking systems (ABS), EBD can apply more or less braking pressure to each wheel in order to maximize stopping power whilst maintaining vehicular control. Typically, the front end carries more weight and EBD distributes less braking pressure to the rear brakes so the rear brakes do not lock up and cause a skid. In some systems, EBD distributes more braking pressure at the rear brakes during initial brake application before the effects of weight transfer become apparent.
Wheel alignment, which is sometimes referred to as breaking or tracking, is part of standard automobile maintenance that consists of adjusting the angles of wheels to the car manufacturer specifications. The purpose of these adjustments is to reduce tire wear and to ensure that vehicle travel is straight and true. Alignment angles can also be altered beyond the maker's specifications to obtain a specific handling characteristic. Motorsport and off-road applications may call for angles to be adjusted well beyond normal, for a variety of reasons.
Torque steer is the unintended influence of engine torque on the steering, especially in front-wheel-drive vehicles. For example, during heavy acceleration, the steering may pull to one side, which may be disturbing to the driver. The effect is manifested either as a tugging sensation in the steering wheel, or a veering of the vehicle from the intended path. Torque steer is directly related to differences in the forces in the contact patches of the left and right drive wheels. The effect becomes more evident when high torques are applied to the drive wheels because of a high overall reduction ratio between the engine and wheels, high engine torque, or some combination of the two. Torque steer is distinct from steering kickback.
Plus sizing is the practice of replacing an automotive wheel with one of a larger diameter fitted with a new tire of lower aspect ratio so that the new tire has close to the same diameter and circumference as the original tire to minimize any changes in speedometer accuracy, torque and traction control, while reducing sidewall flex and (generally) increasing cornering ability.
Lift-off oversteer is a form of sudden oversteer. While cornering, a driver who closes the throttle, usually at a high speed, can cause such sudden deceleration that the vertical load on the tires shifts from rear to front, in a process called load transfer. This decrease in vertical load on the rear tires in turn decreases their traction by lowering their lateral force, making the vehicle steer more tightly into the turn. In other words, easing off the accelerator in a fast turn can cause a car's rear tires to loosen their grip so much that the driver loses control and drifts outwards, even leaving the road tailfirst.
Bicycle and motorcycle dynamics is the science of the motion of bicycles and motorcycles and their components, due to the forces acting on them. Dynamics falls under a branch of physics known as classical mechanics. Bike motions of interest include balancing, steering, braking, accelerating, suspension activation, and vibration. The study of these motions began in the late 19th century and continues today.
Motorcycle components and systems for a motorcycle are engineered, manufactured, and assembled in order to produce motorcycle models with the desired performance, aesthetics, and cost. The key components of modern motorcycles are presented below.
An automobile skid is an automobile handling condition where one or more tires are slipping relative to the road, and the overall handling of the vehicle has been affected.
Crosswind stabilization (CWS) is a relatively new advanced driver-assistance system in cars and trucks that was first featured in a 2009 Mercedes-Benz S-Class. CWS assists drivers in controlling a vehicle during strong wind conditions such as driving over a bridge or when overtaking a semi-truck. CWS uses yaw rate, lateral acceleration, steering angle, and velocity sensors to determine how much assistance to give the driver in a certain scenario whether it be at different speeds or while turning. Using different components throughout the vehicle like brakes, differentials, and suspension, CWS can implement the readings from force sensors to properly assist the driver in a given situation.
