Best winter tires; Radial tire

A radial tire (more properly, a radial-ply tire) is a particular design of automotive tire (in British English, tyre). The design was originally developed by Michelin in 1946 [1] but, because of its advantages, has now become the standard design for essentially all automotive tires.

Tires are not fabricated just from rubber; they would be far too flexible and weak. Within the rubber are a series of plies of cord that act as reinforcement. All common tires (since at least the 1960s) are made of layers of rubber and cords of polyester, steel, and/or other textile materials. This network of cords that gives the tire strength and shape is called the carcass.

In the past, the fabric was built up on a flat steel drum, with the cords at an angle of about +60 and -60 degrees from the direction of travel, so they criss-crossed over each other. They were called cross ply or bias ply tires. The plies were turned up around the steel wire beads and the combined tread/sidewall applied. The green (uncured) tire was loaded over a curing bladder and shaped into the mould. This shaping process caused the cords in the tire to assume an S shape from bead to bead. The angle under the tread stretched down to about 36 degrees. This was called the Crown Angle. In the sidewall region the angle was 45 degrees and in the bead it remained at 60 degrees. The low crown angle gave rigidity to support the tread and the high sidewall angle gave comfort.

By comparison, radial tires lay all of the cord plies at 90 degrees to the direction of travel (that is, across the tire from lip to lip). This design avoids having the plies rub against each other as the tire flexes, reducing the rolling friction of the tire. This allows vehicles with radial tires to achieve better fuel economy than vehicles with bias-ply tires. It also accounts for the slightly “low on air” (bulging) look that radial tire sidewalls have, especially when compared to bias-ply tires.

Construction

As described, a low radial tire would not be sufficiently strong and the surface in contact with the ground would not be sufficiently rigid. To add further strength, the entire tire is surrounded by additional belts that are oriented along the direction of travel. First made of tire cord, these belts were made of steel (hence the term steel-belted radial) by 1948 and subsequently Polyester or later Aramid fibers such as Twaron and Kevlar.

In this way, low radial tires separate the tire carcass into two separate systems:

  • The radial cords in the sidewall allow it to act like a spring, giving flexibilty and ride comfort.
  • The rigid steel belts reinforce the tread region, giving high mileage and performance.

Each system can then be individually optimized for best performance.

Application

Radial tires have different characteristics of springiness from those of bias-ply tires, and a different degree of slip while steering. They ride differently; North American motorists were not accustomed to the feel. Hence the suspension systems of cars had to be modified. Ford Motor Company engineer Jack Bajer experimented in the 1960s on a Ford Falcon, by giving it less tight steering, and adding both isolators to the drive shaft and bushings to the suspension, the latter being to absorb the thump of riding over asphalt expansion joints in a concrete roadway. Cars could now be made lighter because they would not have to make up for the deficiences of bias-ply tires .

  • The Radial Revolution (story of Jack Bajer)
  • ClassicCar.com: Usage of Radial and Bias-ply Tires on Older Vehicles
  • Snow Tires The rationale was that this would provide the best forward traction. In fact, putting only two winter tires on a vehicle can change the vehicle's handling
  • Why to buy snow tires - CNN.com "They key of a true winter tire's capability is that you have a specialist, he said. "A product that is designed to work the best in the cooler winter

Motorcycle snow tires; Nokian Tyres

Nokian Tyres plc () is a Finnish manufacturer of tires for cars, trucks, heavy duty equipment and bicycles. It is the largest car tire manufacturer in the Nordic region. Headquartered in Nokia, Finland, Nokian (which were originally branded as Nokia tires), was split from the then conglomerate Nokia (which later became worlds largest mobile phone vendor) in 1988. Nokia Corporation no longer has any ownership-interest in Nokian Tyres, whose largest shareholder (with an 18.9% stake) is the Japanese tire vendor Bridgestone. However, Nokian Tyres still operates as an independent company.

In the bicycle industry they are known as one of the few manufacturers of metal studded snow tires.

Nokian Tyres also runs the Vianor tyre chain, which is the largest and most extensive tyre franchise in the Nordic countries with approximately 190 retail outlets across Finland, Sweden, Norway, the Baltic countries and Russia.


Firestone snow tires; Body lift

A body lift is a common and cheap method to run larger tires on a vehicle. It involves installing a puck where the body mounts to the frame in order to increase the clearance between tires and the body. This is often used to allow the placement of a larger motor for an engine swap. It is considered by many to be inferior to a well built suspension lift. The downfall to installing pucks for spacing is that over time the rubber in the puck tends to deteriorate. This causes the body to sag, and will eventually become unsafe. While the controversy continues about body lifts verses suspension lifts, a properly installed aftermarket body lift kit can give the desired effect just as safely as a suspension lift.


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