Tires for snow Articles

A tire-pressure gauge is a pressure gauge used to measure the pressure of tires on a vehicle.

Most owner’s manuals recommend checking tire “gauge” pressure (cold inflation pressure) at least once a week at vehicle start but most owners only check their tire pressure when they realize that their tire is nearly flat, which can negatively affect ride quality, fuel consumption and car safety.

Environmental conditions can introduce a 13% to 15% variability in pressure due to temperature (0 °C to 40 °C), and additional changes can result due to altitude. Most car owner manuals do not state rated pressure as a function of temperature or altitude and leave it to the user to make appropriate measurements.

Since tires are rated for specific loads at certain pressure, it is important to keep the pressure of the tire at the optimal amount. Tires are rated for their optimal pressure when cold, meaning before the tire has been driven on for the day and allowed to heat up, which ultimately changes the internal pressure of the tire due to the expansion of gasses. The accuracy of a typical mechanical gauge as shown is +/- 3 PSI. Higher accuracy gauges with +/- 1 PSI accuracy can also be obtained.

Built in tire pressure sensors

Many modern cars such as the Cadillac SRX and Jeep Liberty now come with built in tire pressure sensors that allow all four tire pressures to be read simultaneously from inside the car.

As of 2005, most on-board TPMS utilized indirect pressure monitoring. The anti-lock brake sensors detect one tire pulling more than the rest and indicate a low tire pressure to the driver.

Regulations on tire pressure

By September 2007 all new automobiles below 10,000 pounds sold in the United States will be required to incorporate a direct pressure measurement for each tire. The driver must be notified if any tire is underflated by 25% or more than the rated placard[1] tire pressure.

Introduction

Tires provide for steering, traction, braking, and load support by transmitting forces between the vehicle and the road. Radial Force Variation (RFV) is a property of a tire that characterizes its dynamic behavior of these forces. High values of RFV for a given tire reflect a high level of manufacturing variations in the tire structure that will impart ride disturbances into the vehicle in the vertical direction. RFV is measured according to processes specified by the ASTM International in ASTM F1806 – Standard Practice for Tire Testing.

RFV can best be explained by example. Assume a perfectly uniform tire mounted on a perfectly round wheel loaded with a constant force against a perfectly round test wheel. As the wheel turns, it turns the tire, and the tire carcass undergoes repeated deformation and recovery as it enters and exits the contact area. If we measure the radial force between the tire and the wheel we will see zero change as the tire turns. If we now test a typical production tire we will see the radial force vary as the tire turns. This variation will be induced by two primary mechanisms, variation in the thickness of the tire, and variation in the elastomeric properties of the tire.

Consider a good tire with RFV of 6 pounds. This tire will induce a 6 pound force upward into the vehicle every rotation. The frequency of the force will increase in direct proportion to rotating speed. Tire makers test tires at the point of manufacture to verify that the RFV is within allowable quality limits. Tires that exceed these limits may be scrapped or sold to markets that do not require stringent quality.

Spring Model

RFV is often explained by modeling the tire as being a ring comprised of short compression springs. As the tire turns a spring element makes contact with the road and is compressed. As the spring rotates out of the contact area it recovers to its original length. In practice, these springs have slight differences in their lengths and spring constants. These variations result in RFV.

Tires are complex composite structures made of many different components that are assembled on a drum and cured in a mold. As a result there are many conditions that result in RFV. These include variations in: tread extrusion thickness and symmetry, tread splice, body ply splices, inner liner splice, bead symmetry, turn-up symmetry, building drum alignment, transfer ring alignment, curing press bead seating, shaping bladder alignment and control, mold runout, and mold alignment. All of these factors can lead to variations in the material distribution and thickness that are modeled as spring length. The various tire components also are made from different materials, each of which exhibit variation in their elastic properties. These variations are influenced by rubber viscoelastic properties, mixing dispersion and uniformity, and cure heat history, among other things.

Waveform Analysis

RFV is a complex waveform. It is expressed using several standard methods, including peak-to-peak, first harmonic, second harmonic, and higher-order harmonics. In production RFV testing these are reported as both magnitudes and angles.

This article is about the snow formation. For the architectural use, see cornice.

In climbing, a cornice is an overhanging edge of snow on a ridge or the crest of a mountain which are built up by drifting snow. Cornices are extremely dangerous and should never be walked on or under without adequate protection, or if other options are either not available or are more hazardous.

When a cornice collapses, it breaks in from the cornice to the top of the peak; even being on the snow on top of rock exposes you to hazard in this situation. The best practice in mountaineering is to stay far enough back from the edge so as not to be able to see the drop, as an approximate metric of exposure. Of course, this is not always possible. A good test for safety (in sunny weather) is to insert an ice axe and see if a blue glow comes out the hole. This indicates the ice is being lit from underneath, and that the climber should retreat to a safer location.

SNoW (pronounced: “Snow”, born June 11, 1985 in Tokyo, Japan) is a J-Pop singer. She currently attends Santa Monica College in California. She has grown up in a bilingual environment. Her favorite artists include Ani DiFranco, Iggy Pop, Talking Heads, and Jack Johnson.

Her debut single Yes was released under an indie record label in November 2004. In 2005, she switched labels to Sony Music Entertainment Japan and released Hanabi made Ato Sukoshi (花火まであとすこし - unofficial translation: “A Little Longer Until the Fireworks”) in July. Her third single, Sakasama no Chō (逆さまの蝶 - unofficial translation: “The Inverted Butterfly”), was released on January 25, 2006. Sakasama no Chō was the opening theme of the 2005/2006 anime Jigoku Shoujo (地獄少女), and will be inserted into the movie Humoresque ~Sakasama no Chō~, to be released in February 2006. The opening theme for Jigoku Shōjo’s second season, NightmaRe, was also performed by SNoW, and was released as a single on December 6, 2006.

Albums

初雪(Hatsuyuki) - January 23, 2007

External links

Official websites in Japanese:

• SNoW Official Site
• SNoW - www.sonymusic.co.jp
• Humoresque