Tire Tips

 
by Tireman Info 16. May 2012 16:07

Reading Your Sidewall
There is a lot to learn from the sidewall of your tire. Although at first glance you may think you stumbled across tire hieroglyphics, you've actually found molded into the tires side its own user manual.

Example Tire Size: P205/55R16 91W
P identifies your tire as a Passenger Tire. The P stands for PMetric. If your tire size starts with LT rather than a P than it identifies the tire as a light truck tire.

205 identifies the tire section width, which is the measurement of the tire from sidewall to sidewall in millimeters. This measurement varies depending on the rim to which it is fitted.

(There are 25.4 millimeters per 1 inch.)

55 is the two-figure aspect ratio. This percentage compares the tire's section height with the tire's section width. For example, this aspect ratio of 55 means that the tire's section height is 55% of the tire's section width.

R indicates the construction used within the tire's casing. R stands for radial construction. B means belted bias and D stands for diagonal bias construction.

16 The last dimension listed in the size is the diameter of the wheel rim, which is most often measured in inches.

Load Index and Speed Rating

91 The load index and speed rating, or service description, are the numbers that follow the tire size.

The load index tells you how much weight the tire can support when properly inflated. Load indices range from 75 - 105 for passenger tires, with each numeric value corresponding to a certain carrying capacity. The carrying capacity for each value can be found on a load index chart. On each U.S. passenger car tire, the load limit is listed in pounds. European tires have the load limit listed in kilograms and sometimes pounds.

W Speed ratings are represented by letters ranging from A to Z. Each letter coincides to the maximum speed a tire can sustain under its recommended load capacity. For instance, S is equivalent to a maximum speed of 112 mph. Even though a tire can perform at this speed, continental tire does not advocate exceeding legal speed limits.

DOT Serial Number
The "DOT" symbol certifies the tire manufacturer's compliance with the U.S. Department of Transportation tire safety standards. Tires made in the United States have the DOT serial number located on the inside sidewall near the rim.

Below is a description of the serial number. Starting with the year 2000, four numbers are used for the Date of Manufacture, the first two numbers identify the week and the last two numbers identify the year of manufacture.

Prior to year 2000, three numbers are used for the Date of manufacture, first two numbers identify the week and the last number identifies the year of manufacture. To identify tires manufactured in the 90s, a decade symbol (a triangle on its side) is located at the end of the DOT serial number.

How to Build a Radial Tire
Tires are not just round and black -- they are sophisticated products that can take years of research and development to produce. If you have ever wondered how tires are made, the following is a roadmap for the construction of a radial tire:

Start with Rubber and Additives
Tire construction starts when raw chemical additives such as sulfur, carbon black and solvents are combined with natural and synthetic rubber. The process takes place in a large machine called a banbury.

In addition to mixing and grinding, the banbury heats the rubber to make it workable in preparation for further applications. The raw product emerges in the form of long, flat bands of rubber, which are then worked in rolling mills.

Six Main Components

  • It takes several machines to shape the rubber into the individual components of the tire: tread, ply, belts, beads, sidewalls, and innerliner.
  • The tread rubber is extruded through a tuber, then measured, cooled and cut into precise lengths. Sidewalls are also extruded through tubers, along with the white rubber for a white sidewall or white lettered tire if required.
  • The ply is produced in a calender mill, which combines thin sheets of rubber and fabrics like nylon or polyester. The large sheets are cut to width, rolled and transported to the assembly area where all the components will come together.
  • At the same time as the raw rubber is transformed into the tread and plies, the creel room equips the tire with its basic strength. Fine steel wire goes into the manufacturing of belts for the steel-belted radial tire. Rubber from the mills and steel from the creel room are molded together into wide flat sheets, cut on the bias, rolled, and moved to the tire-building machine.
  • The innerliner is an impermeable layer of rubber on the inside of a tire which creates an airtight chamber when fitted to the vehicle wheel. This layer eliminates the need for an innertube.
  • The last major component of the tire is the bead. The beads are created out of wrapped steel wire, covered with rubber and formed into hoops. The bead anchors the fabric plies of the tire and seats the tire firmly on the wheel.

The Green Tire
The six components (tread, ply, belts, sidewalls, liner and beads) come together on the tire-building machine. These six components are assembled into what is known as an uncured, or green, tire in two stages.

The carcass of the tire, including beads, plies, sidewalls and liner, is constructed on one side of the machine. The tread and the underlying belts are assembled next to the carcass on the other side of the machine. The two sub-assemblies are then joined together and the result is a green tire.

Vulcanization
The next phase is vulcanization, the molecular transformation of the soft, gummy green tire into the tough, and long-wearing, modern passenger tire. The green tire is placed in a curing mold and is subjected to intense pressure and high heat internally and externally for a specified period of time. Simultaneously, the tread pattern is imprinted onto the rubber. When it comes from the mold, the tire is ready for final finish and inspection.

Final Finish and Inspection
For showroom quality, any excess rubber is trimmed off the cured tire. Every tire is thoroughly inspected. The tire then undergoes various uniformity checks to assess ride and comfort quality. Once the tires have passed all the checks and inspections, they are sent to the distribution warehouse for shipment.

History of the Passenger Tire
Dateline 3500 B.C.--Today, man invented the greatest invention ever seen, THE WHEEL!

Thousands of years later, the wheel has come a long way. For one thing, it is no longer made of wood and it is guaranteed that the ride is much smoother. What hasn't changed is the fact that it is still one of man's greatest inventions. Could you imagine where we would be today without it?

The early wheel was very simple: a solid curved piece of wood. Later, leather was added to soften the ride. As time progressed it became solid rubber, which led to today's tire--the pneumatic, or air inflated, radial tire.

The first wheels made of metal or wood were very durable but did not provide a very comfortable ride. The nearest thing to the first tire was a metal hoop. There were many individuals that made contributions in creating the tire as we think of it today.

Vulcanization and Charles Goodyear
Rubber was not always as useful as it is today. Early rubber did not hold shape; it would be sticky in hot weather and become inflexible in the cold.

In 1839 Charles Goodyear was credited with the discovery of the vulcanization process. Vulcanization is the process of heating rubber with sulfur. This transforms sticky raw rubber to firm pliable material, which makes rubber a perfect material for tires.

The story of Charles Goodyear is a sad one. Although he dedicated his entire life to making rubber a better form, he would never profit from all his work. Charles Goodyear died bankrupt.

Forty years later, a rubber company would honor his hard work by using his name for their new tire company.

Solid Rubber Tires
Soon after the discovery of vulcanization, tires were made out of solid rubber. These tires were strong, absorbed shocks and resisted cuts and abrasions. Although they were a vast improvement, these tires were very heavy and did not provide a smooth ride.

Today there are still types of tires made of solid rubber.

Pneumatic Tires
The pneumatic tire uses rubber and enclosed air to reduce vibration and improve traction. Robert W. Thomson, a Scottish engineer, first patented the air-filled tire. Unfortunately the idea was too early for its time and was not a commercial success.

In 1888 John Boyd Dunlop of Belfast, Ireland, became the second inventor of the pneumatic tire. Dunlop claimed to have no knowledge of Thomson's earlier invention.

The second time around, the pneumatic tire caught the public's attention. The timing was perfect because bicycles were becoming extremely popular and the lighter tire provided a much better ride.

Bias Ply Tires
For the next fifty years, vehicle tires were made up of an inner tube that contained compressed air and an outer casing. This casing protected the inner tube and provided the tire with traction.

Layers called plies reinforced the casing. The plies were made of rubberized fabric cords that were embedded in the rubber. These tires were known as bias ply tires. They were named bias ply because the cords in a single ply run diagonally from the beads on one inner rim to the beads on the other. However, the orientation of the cords is reversed from ply to ply so that the cords crisscross each other.

Today you can still find bias-ply tires as authentic equipment for antique and collector cars, as well as for certain type of off-the-road tractor tires.

Radial Tires
The first introduced steel-belted radial tires appeared in Europe in 1948. Radial tires are so named because the ply cords radiate at a 90 degree angle from the wheel rim, and the casing is strengthened by a belt of steel fabric that runs around the circumference of the tire.

Radial tire ply cords are made of nylon, rayon or polyester. The advantages of radial tires include longer tread life, better steering and less rolling resistance, which increases gas mileage. On the other hand, radials have a harder riding quality and are about twice as expensive to make.

Driving Tips for Wet Roads
Driving in the rain can be dangerous; in fact thousands of car accidents each year are caused by wet driving conditions.

Routinely Check Your Tires
It is a good idea to always check your tires before you hit the road. To ensure your tires are working at their best, make sure you do the following routine maintenance:

  • Keep your tires properly inflated. The correct air pressure for your tires is specified by the vehicle manufacturer and can be found on the vehicle door edge, doorpost, glove box door or fuel door. It is also listed in the owner's manual. The number listed on the side of the tire is not the recommended air pressure for your tire -- it is the maximum air pressure for the tire. You should check your tire's air pressure at least once a month.
  • Check the tires tread depth. Tires should have 1/16 inch tread depth in order to perform the in the way for which they were designed. Proper tread depth will help prevent skids and hydroplaning.
  • Have your tires rotated at least every 6,000 - 7,000 miles. This will aid in detecting alignment problems and help prevent irregular wear.

    Slow Down
    As rain falls, it mixes with grime and oil on the road creating slick conditions perfect for skids. The best way to avoid skidding is to slow down. Driving at a slower pace allows more of the tire's tread to make contact with the road, which leads to better traction.

Recover From a Skid
Skids can even happen to the most cautious drivers. If your car does skid, remember not to slam on the brakes, and do not pump the brakes if you have an anti-lock braking system (ABS). Instead apply pressure to the brakes in a firm manner and steer the car in the direction of the skid.

Keep a Safe Distance
It takes about three times longer to break on wet roads than on dry roads. Since more distance is required to brake, it is important not to tailgate. Keep more than two car lengths between you and the vehicle in front of you.

Recover from Hydroplaning
When it rains, water creates a barrier between the road and your tires. The liquid film that forms can cause you to lose traction and glide or hydroplane across the water's surface. If this happens, do not brake. It is better to take your foot off the gas, hold the steering wheel in place, and lightly apply the brakes. If you have a manual transmission, push in the clutch and let the car slow down on its own.

Maintenance
Your tires are the only part of your vehicle that actually touches the road when you drive. It only takes a couple of minutes of maintenance each month to keep your tires working at their best.

Check Your Air Pressure Once a Month
Incorrect air pressure is the leading cause of tire damage. To avoid tire damage you need to check your tire's air pressure once a month.

The correct tire pressure can be found in the following places:

  • in the car's owner's manual
  • gas tank lid
  • driver's side door's edge
  • doorpost
  • The air pressure listed on the side of your tire is NOT the correct air pressure for your vehicle. That number is the maximum air pressure for the tire.

Don't get stranded and avoid costly towing expenses. Check your air pressure on your spare regularly. Note: If you have different rims than came on your vehicle originally, make sure that the bolts on your spare tire are the correct fitting.

Failure to keep your tires properly inflated can increase wear and will have a negative effect on your vehicles handling.

When checking and adjusting tire pressure, the following should be kept in mind:

  • Check the air pressure when the tire is cold - tires become hot even after driving just a mile. If you must drive to add air, check your air pressure before you leave. Air pressure changes 1-2 pounds for every 10 degrees of temperature change. Air pressure goes up in warm weather and down in cold weather.
  • Tire pressure must be the same on the tires of each axle, but may be different on the front and rear axle.
  • Valve caps must be tightly closed to protect the valve from dust and dirt and prevent it from leaking.
  • Replace missing valve caps without delay.
  • Take this opportunity to inspect your tires to make sure there are no punctures and they are free of deformities.

Tread Depth
To prevent hydroplaning and skidding, your tires must have proper tread depth. The minimum tread depth is 1/16th of an inch.

Ask anyone: the easiest way to check your tread depth is the penny test. Take a penny and place it in the tread of your tire. If part of Lincoln's head is covered by the tread, your tires have enough tread. If you can see Lincoln's entire head, you should buy a new tire.

You should also check your tire tread for uneven wear. Irregular wear shortens the life of your tires. If you think you have uneven wear, you should take you vehicle to Tireman.

Rotation
The best way to prevent uneven wear is to have your tires rotated every 5,000 - 7,000 miles or as specified in your vehicle's owner manual.

Potential Tire Troubles

  • Curbs can prove to be big trouble to your tires. Approach curbs with care, if you drive over them too fast or at the wrong angle the impact may cause the tire to crack.
  • Avoid potholes or debris in the road when possible.
  • Avoid fast stops & starts.
  • Be sure to check your owner's manual for your vehicles maximum load. Overloading your vehicle can shorten your tire life.
    Replacing Your Tires

You should replace your tires with the same type of tires that came on your vehicle original equipment. This includes tire size, type and speed rating.

Safe Winter Driving
Thanks to their special compound, winter tires offer the elasticity required to ensure maximum grip throughout the cold season, regardless of the road conditions. Summer tires can become hard when the temperature falls below 45 degrees, thereby losing the flexibility needed to build up sufficient grip for braking, starting off and cornering. Because of their greater suppleness in the cold, winter tires are able to interlock with asphalt, snow and ice, even at lower temperatures.

Here a few tips to keep you from slipping and sliding on the way to work in the morning:

  • Listen to the weather report the evening before. If snow is predicted, you should plan to get going earlier, because of traffic jams and delay. In really treacherous weather, the safest thing to do is stay home.
  • Before taking off, make sure all car windows are completely clear of snow and ice; if you try to get by with just a peephole, you may end up sharing the blame for an accident.
  • Check your rearview mirror and then test your brakes as soon as it is safe to do so. This will give you a feeling for road conditions.
  • Avoid shortcuts via residential side streets. These roads are cleared last, if at all.
  • Allow an extra wide safety margin when stopping at traffic lights and intersections and pay close attention to the vehicles in front of you.
  • Avoid braking just before the intersection, where it is usually especially slippery.
  • Be especially careful when crossing bridges! They can be treacherously slippery in winter because they are "cooled" from above and below. Fog can form ice on very cold days and make roads slick.

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How to | Tire Tips

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