Snow chains for tires Information

The Treadwear Grade of a tire is the numeric portion of the Uniform Tire Quality Grade Standards (UTQG) that are printed on the sidewall of a tire. These standards were enacted by the National Highway Traffic Safety Administration (NHTSA), which is part of the United States Department of Transportation. Higher treadwear numbers indicate that the tread of a tire, and hence the tire itself, should last longer, although this is more true within a single product line than when comparing the product lines of different manufacturers.

Methodology

The wear on tires that are being tested (”candidate tires”) is compared to the wear of Course Monitoring Tires (CMT), which are sold by the NHTSA at its UTQG test facility in San Angelo, Texas. Both types of tires are mounted on vehicles that will be driven in a convoy during the test, thus ensuring that the candidate tires and the CMT tires experience the same road conditions. The convoy, typically one of four or fewer vehicles, will drive 7200 miles on public roads in West Texas. Candidate tire wear will be checked during and after the test, and compared to the wear on the CMT tires from the same convoy.

The first CMTs were commercially-available Goodyear Custom Steelguards, and Goodyear Tire and Rubber Company produced all CMT tires from 1975 until 1984. From 1984 to 1991, the CMT tires were produced by Uniroyal. CMT tires are now “specially designed and built to American Society for Testing and Materials (ASTM) standard E1136 to have particularly narrow limits of variability.” 1.

Treadwear Grade Number

The treadwear grade describes how long the tire manufacturer expects the tire to last. A Course Monitoring Tire (the standard tire that a test tire will be compared to) has a rating of “100″. If a manufacturer assigns a treadwear rating of 200 to a new tire, they are indicating that they expect the new tire to have a useful lifespan that is 200% of the life of a Course Monitoring Tire.

Limitations

The DOT does not test tires. It depends on manufacturers to test their own tires and report the results. Unfortunately, this system has made treadwear ratings far less useful than the DOT had originally intended because tire manufacturers are able to use the treadwear grade as a marketing tool.

It is legal and permissible for a manufacturer to give their tire a 240 rating when their competitor’s equivalent tire has a 220 rating; thus creating the false impression that the 240 tire is a better purchase because it will last longer. This tendency to inflate treadwear numbers has become so common that some manufacturers may report that ALL their tires have above average treadwear grades. Some are taking normal tires and reporting a treadwear of 600 or more, or giving a 220 rating to maximum performance tires with a reputation for poor tire life (e.g. the Goodyear Eagle F1 Supercar EMT).

TreadWear Grade

Below 200=15% of Tires

201 - 300=25% of Tires

301 - 400=32% of Tires

401 - 500=20% of Tires

501 - 600=6% of Tires

above 600=2% of Tires

Source: safercars.gov

Trends

In general, manufacturers tend to overstate the treadwear of their tires in an effort to create the impression that their tires last a long time. The exception to this is in competition racing tires, which customers expect to have very soft rubber compounds and very short lifespans. Manufacturers tend to give their race tires low treadwear numbers (often zero) to emphasize how soft and sticky their rubber is.

Uses

The ability of manufacturers to report their own numbers makes comparison of treadwear ratings between companies useless. Ratings may still be useful within a manufacturer’s own line of tires. For example, a customer can reasonably assume that the higher treadwear rating on a Dunlop SP 60 means it will last longer than the Dunlop SP Sport.

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Firehawk may refer to:

• A GDI unit in Command and Conquer.
• Firehawk, DC Comics superheroine
• Firehawk, roller coaster at Kings Island amusement park near Cincinnati, Ohio
• The Sikorsky S-70A Firehawk, a medium-lift helicopter
• The Firehawk, a factory performance option of the Pontiac Firebird
• Firehawk, a 1993 film
• Tom Clancy’s Firehawk, a rumored new video game from the Tom Clancy franchise of games
• Firestone Firehawk, a sub-brand of performance tires by Firestone Tire and Rubber Company
• IMSA Firestone Firehawk Endurance Championship, a showroom stock car championship ran by the International Motor Sports Association and sponsored by Firestone Tire and Rubber Company.

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Whitewall tires are tires that have a stripe of white rubber on the outer sidewalls. The early tires were made with rubber that is naturally white. However, the white rubber did not offer sufficient traction and endurance so carbon black was added to the rubber used for the treads. This resulted in tires with both sidewalls of white rubber. Next came the tires built with all black rubber and white rubber was added to make the whitewalls. The original whitewalls featured an entirely white sidewall. Modern whitewall tires often have a thin white stripe, or white raised lettering identifying the tire manufacturer and tire model.
Such tires were made with a full strip of white rubber under the black. The raised white letters were revealed by buffing the cured tire sidewall.
The black covering strip was made of Neoprene (polychloroprene) to avoid staining.

Classic vehicles have usually been optioned with wide whitewalls - it was popular during the pre and post-war era, only to resurface in the 1970s as a limousine trademark and within the pimpmobile culture. Although wide whitewalls are rare on modern automobiles, they are still manufactured by specialty outlets and/or classic car restoration companies such as Diamond Back Classics, Coker Tire and Vogue Tyre Company. Some companies manufacture wide whitewall inserts - the Portawall inserts are usually sold through VW Beetle restoration companies. (Port-A-Walls should not be used with radial tires due to the flexing of the sidewall that creates friction and rubbing between the port-a-wall and the tire )

Wide Whitewalls were popular on classic cars produced 1961 and earlier, lowrider and Cadillacs. Beginning with the 1962 Chevrolet Impala SS the whitewalls were reduced to 1″ wide with black between the rim and the whitewall. Modern trends toward more minimal styling, and large rims favoring low-profile tires leave little room for a whitewall. With the introduction of the new “retro”-styled Ford Thunderbird, Chrysler PT Cruiser, and Chevrolet HHR, wide whitewalls are again becoming popular. They are also an avalibale factory option on the Lincoln Town Car.

Gallery

Other cars with whitewall tires:

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In the sport of cycling, a chain gang is a group of cyclists in a close knit formation usually of two parallel lines.

The formation comes from the fact that it is harder to cycle at the front of a group than in the shelter of another rider. The rider behind enjoys the slipstream of the rider in front. If one rider were to stay at the frontall the time, he would tire and the whole group would slow down. If the lead is rotated, the effort is and the speed can be higher or the effort less.

The name chain gang is an allusion to the formation that riders adopt. The rider on the front of the group will take his share of the lead, then swing to the side and let the rest of the line come through, led by a new leader. The first man then eases up and drops in behind the last rider in the line, staying in his slipstream until once again his turn comes to ride at the front.

When there are enough riders, turns at the front can be so brief that there is a continuous flow up and down, in two lines, so that cyclists take on the role of links in a chain. For that reason: chain gang.

The technique is hard to perfect because it demands riders cycle close to the rider in front at speed, sometimes just centimetres from his tyre. It also demands trust in others in the group because, that close, no rider would be able to avoid hitting the one in front if the pace suddenly changed. For that reason, the leading rider takes reponsibility for taking the line through the smoothest path he can and at a constant speed.

The technique is often used in training for races but it can be seen in races themselves, usually when a small group of riders gets ahead of the main field, or in team time-trials, where the chain-gang technique is paramount.

Chain gangs can also be referred to in the US as pace lines and in the UK as bit-and-bit.

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The tread of a tire or caterpillar track refers to the rubber on its circumference that makes contact with the road. As tires are used, the tread is worn down limiting their effectiveness in providing traction. A worn tire tread can be replaced using a process known as retreading. The word tread is often used incorrectly to refer to the pattern of grooves cut into the rubber. Those grooves are correctly called the tread pattern, or simply 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. Generally there is a tradeoff of tread friction capability; deeper patterns often enhance safety, but simpler designs are less costly to produce and actually may afford some roadway noise mitigation. Tires intended for dry weather use will be designed with minimal pattern to increase the contact patch. Tires without any tread patterns are known as slicks and are generally used for racing only, since they are quite dangerous if the road surface is wet.

Street tires will also include wear limit indicators in the form of small raised bridges within the grooves. When the tread is worn down enough that the limit indicators make contact with the road, the tire is deemed to be at the end of its service life. Brake pads use similar indicators in the form of notches on their surface that disappear when they are used.

Off-road tires

Off-road tires used in mud or dirt feature individual knob patterns to allow the tire to bite into the surface and leverage the sides of the tread to get a better grip. Given the smaller contact patch, these tires tend to wear quickly when used on asphalt.

Mountain bike & motorcycle tires

Mountain bike and some motorcycle tires feature tread patterns similar to off-road tires used on cars and trucks but may sometimes include an unbroken tread that runs along its center. This feature provides better traction and lower noise on asphalt while the bike is vertical while retaining its ability to provide lateral grip when the bike is leaning.

Caterpillar tracks

Caterpillar tracks such as those used on military tanks or construction machines have metal track segments which may be rubber-coated. They usually do not feature tread patterns, because these would offer little additional grip given the weight of the tracked vehicle.

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Snow chains, or tire chains, are devices which are affixed to the wheels of vehicles to provide superior traction when driving through snow and ice. Snow chains are usually attached to the drive wheels of a vehicle (e.g. the front wheels on a front-wheel drive car), though all four wheels may be chained to provide extra stability. Some owner’s manuals for four-wheel drive cars specify that two specific wheels can be chained, leaving the other two unchained if necessary.

Snow chains are paired into 2 sets of chains. You should buy chains that match your tire size (tire width and radius numbers can be found printed on the tire).

A set of chains are placed on the wheels that are connected to the drive train in order to gain traction in icey, snowy or muddy conditions.

Front Wheel Vehicles:
Most passenger cars are front wheel powered vehicles, so the snow chains would be placed on the 2 front tires.

Rear Wheel Vehicles:
Pickup trucks and older cars are usually rear wheeled drive so the chains are placed on the rear tires.

4 Wheel Vehicles:
4 wheel vehicles can use 2 sets of chains on all 4 wheels. With only 1 set of chains they are often put on the rear wheels, but can be placed on the front wheels instead for the added steering benefit.

In snowy conditions, transportation authorities often require snow chains to be fitted on vehicles that lack four-wheel drive and proper tires. These requirements are usually enforced by checkpoints, before which eligible drivers must have snow-chains fitted on their cars. Near such checkpoints, chains can often be fitted professionally for a fee. Snow chains limit the speed of the automobile to approximately 30 mph (50 km/h), but in deep snow the chains can be very useful.

Purchasing the right size chains for your tires

U.S. tires have standardized sizing information. This information can be found on the sidewalls of the tires. The first letter(s) is for the vehicle type, P for passenger, LT for light truck. The next 3 digit number gives the tire’s width in millimeters. The next 2 digit number gives the tire’s height to width ratio. The next letter is R, which stands for radial ply tires (not radius) followed by the last 2 digit number, which is the rim diameter for the vehicle’s wheels.

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Greek National Road 38 is a highway linking the cities of Agrinio, Karpenisi and Lamia. It is the only highway linking Agrinio and Larissa because GR-30 is narrow. The highway passes into the reservoir of the Acheloos river and into the Pindus ranges. It later passes through Karpenisi and into the Spercheios valley before ending in Lamia. It runs into the prefectures of Aitolia-Acarnania, Eurytania and Fthiotis.

The highway was mainly gravel from NE of Agrinio up to Eurytania and mainly wasn’t accessible during winter months. It was later paved in the 1990s.

The road is partially snow covered and is accessible only with tire chains throughout the winter months. It happened during heavy snow and blizzard weathers in most areas at the turn of the 20th century and the beginning of the 21st century but not as much as other mountainous roads.

History

In 2001, heavy rainfalls devastated and flooded part of the highway.

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Tire load sensitivity describes the behaviour of tires under load. Conventional pneumatic tires do not behave as classical friction theory would suggest. Friction theory says that the maximum horizontal force developed should be proportional to the vertical load on the tire. In practice, the maximum horizontal force Fy that can be generated is proportional, roughly, to the vertical load Fz raised to the power of somewhere between 0.7 and 0.9, typically.

Production car tires typically develop this maximum lateral force at a slip angle of 6-10 degrees, although this angle increases as the vertical load on the tire increases. Milliken, W.F., Milliken, D.L., 1995, “Race Car Vehicle Dynamics”, Society of Automotive Engineers (SAE) Warrendale, PA. page 27. Formula 1 car tires may reach a peak sideforce at 3 degrees Wright P., 2001, “Formula 1 Technology”, Society of Automotive Engineers (SAE) Warrendale, PA.

Example

As an example, here is data extracted from Milliken and Milliken’s “Race Car Vehicle Dynamics”, figure 2.9:

The same sensitivity is typically seen in the longitudinal forces, and combined lateral and longitudinal slip.

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A snow fence is a structure used to force drifting of snow to occur in a predictable place, rather than in a more natural method. Snow fences are primarily employed to minimize the amount of snow drifting onto roadways. In rural areas, farmers and ranchers may use temporary snow fences to create large drifts in basins for a ready supply of water in the spring.

Snow fences are also used in avalanche control.

A typical style of temporary snow fence seen in North America today is often one of two varieties: orange plastic attached to stakes at regular intervals or a cedar or other lightweight woodstrip and wire fence, also attached to metal stakes. A permanent snow fence is generally of larger wooden poles set deeply into the ground with large wooden planks running vertically across them. A permanent snow fence is built when a roadway is subject to predictable snow and wind patterns each winter, usually in mountain passes.

The drifting of snow behind a fence follows the laws of physics as the pressure on the downwind side is less than that on the windward side, allowing light materials such as snow or leaves to settle there.

Campbell, E. (March 1975). Snowdrift Structures. Avalanche Protection in Switzerland (pp. 103-116). Fort Collins CO: General Technical Report RM-9, USDA-Forest Service.

Mears, A.I. (1992). Avalanche Structural Protection in: Snow - Avalanche Hazard Analysis for Land - Use Planning and Engineering. Denver CO: Colorado Geological Survey, Department of Natural Resources, Bulletin 49.

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Maurice “Morry” Taylor Jr. (1944-) is the President and Chief executive officer of Titan International Inc.. Taylor, nicknamed “the Grizz” for his bear-like gruffness, started in tool and die manufacturing before purchasing Titan Wheel International from Firestone.

Taylor gained brief fame outside the business world when he made an unsuccessful run for the Republican nomination in the U.S. presidential election of 1996, a run chronicled in his book “Kill all the lawyers- and other ways to fix the government”.

Taylor was the one of the subjects on the 19th episode of PRI’s This American Life entitled “Rich Guys”, originally aired on 4/12/1996.

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