Category Archives: Tire Information

Winter Tires: Does a Four-Wheel Drive Vehicle Need Them?

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Dear Tracy,

This fall I replaced my car with a “new” used  four-wheel drive vehicle. The guy I bought it from said that with four-wheel drive I do not have to worry about driving in bad weather.  Now that winter is here I am wondering if this means I do not need snow tires for winter driving. Can you tell me?

Sandy T.

Dear Sandy,

While a four-wheel drive vehicle does provide some performance advantages, driving a truck, SUV or crossover with four-wheel drive does not eliminate the need for winter tires to allow for safe driving in snow and ice.

Four-wheel drive by design does offer more power than two-wheel drive. That is why four-wheel drive vehicles are less likely to get stuck and may accelerate faster. The problem is that winter driving is also about stopping and cornering; without the assistance of winter tires, four-wheel drive offers little advantage in these areas. Additionally, four-wheel drive vehicles tend to be heavier and may take longer to come to a stop.

Winter tires are made from a softer rubber than all season tires, which allows them to provide better road grip and handling. The open tread design is another feature that gives winter tires better handling capability on slush and snow.

Four-wheel-drive vehicles typically come with large, wide tires so it is especially important to consider the switch to winter tires, if you know you will be encountering a lot of snow and slush. Due to the larger surface area of the tires, they may not cut through snow as efficiently and may be likely to hydroplane.

New Year, New Tires

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Dear Tracy,

As the new year approaches, I am coming up with a budget for the major purchases I will need to make. I have had my car awhile, and I think it may be due for a new set of tires in 2014. Is there a certain point at which new tires should be purchased, or are there signs to watch for that will tell me when I need to replace them?

Vanessa A.

Dear Vanessa,

First, let me congratulate you on your wise financial planning. Tires are a significant investment, and it makes sense to plan ahead for the purchase. Now, as to how soon you need to make that purchase – the best way to decide is to let your tires tell you.

Here are four basic things to look for in evaluating the condition of your tires. Any of these signs will mean that it is time to start shopping and get those old tires replaced:

Look at the tread depth. There should never been less than 1/16 of an inch of tread on your tires. How much is a 1/16 of an inch? The easy way to tell is with the penny test. Take your penny and insert it into the tread  with Abe’s head facing toward the tire. If you can see his entire head, that means you do not have enough tread left on your tires to be safe.

Look at the tread wear indicator bars. Newer tire models have tread wear indicator bars, which are designed to help you know when to replace your tires. These bars are mostly invisible when the tires are new and have plenty of tread. As the tire tread wears down, they gradually become visible as flat rubber bars running perpendicular to the direction of the tread. When you see these bars, it is time for new tires.

Check for cracks in the sidewalls. Look for cracks or cuts in the sidewall of each tire. These cracks may appear as lines that are visible to the naked eye. These could indicate that your tire is developing a leak or that it is on the verge of a blow out. If you discover the cracks in the sidewalls of your tires, replace them as soon as possible to avoid a hazardous situation.

Check for blisters or bulges. When the outer surface of a tire begins to weaken, a bulge or blister may appear on the surface of the tire. These tire bulges and blisters are weak or vulnerable spots that can cause a sudden blowout. If you notice this happening on the surface of your tires, it is definitely time to shop for a new set.

 

Tire Pressure Monitoring Systems

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Dear Tracy,

My friend just purchased a new car and one of its features is an internal system that monitors tire pressure. Can you tell me how this system works?

-Becca G.

Dear Becca,

A tire pressure monitoring system, also referred to as a TPMS, is an electronic system that continuously monitors the air pressure of all four tires. The TPMS alerts the driver when tire pressure falls below a preset limit by illuminating a warning light on the dashboard.

As of 2008, the National Highway Traffic Safety Administration has required that all passenger cars, light trucks and vans (Gross weight less than 10,000 pounds) be equipped with a TPMS. Earlier model vehicles can be retro-fitted with a tire pressure monitoring system installed by a qualified service professional.

Tire pressure monitoring systems come in two designs –  direct and indirect. A direct monitoring system places a pressure sensor on each tire, usually on the valve stem or band mounted. The sensors used in direct systems are powered by separate lithium batteries, which ultimately need replacement. This means that direct tire pressure monitoring systems need to be serviced regularly and should be part of scheduled maintenance.

The technology used in indirect tire pressure monitoring systems is based on the calculation of factors, including tire size. The diameter of a tire is smaller when it is not properly inflated, and when one tire is smaller than the other three, it will have to spin faster to keep up. Speed sensors applied at each wheel position identify an underinflated tire by comparing the rotational speed of each wheel with the average speed of all four wheels.  This calculation is used to determine if one is spinning significantly faster than the others, and therefore underinflated. While the indirect system does not require servicing, the design does have some issues, such as the problem that if all four tires are underinflated, the system may not detect an abnormality.

All tire pressure monitoring systems installed on 2008 vehicles and later are required to detect and warn the driver when the system is not functioning properly through a malfunction indicator. For some systems, a malfunction is indicated by a flashing of the low tire pressure warning light for a period 60 to 90 seconds with the warning lamp remaining illuminated following the flash sequence. The flash and illumination sequence will repeat at each subsequent vehicle start-up until the problem is addressed. If your vehicle has a TPMS, be sure that you are familiar with the malfunction warning for your specific system.

Rolling Resistance – What Does it Mean for Tires

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Dear Tracy,

I have heard the term “rolling resistance” used in describing tire features. Can you tell me what rolling resistance means and why it is important?

Amber M.

Dear Amber,

Rolling resistance is a term that describes the force resisting motion as a tire moves along the surface of the road. Most vehicle manufacturers install original equipment tires with low rolling resistance to optimize performance for government Corporate Average Fuel Economy (CAFE) mandate testing. Tires developed for lower weight and rolling resistance are often constructed with thinner sidewalls and shallower tread depths. The materials that go into tires can also have an impact on rolling resistance. While tires with low rolling resistance are good for fuel economy, these tires may not have all the features you need for your replacement tires.

The kind of tire you put on your car should offer both performance and safety for your particular model, as well as the kind of driving you do on a day to day basis. Weather factors may also be a consideration if you happen to live in a climate that experiences extreme conditions on a regular basis.

In today’s market, most tire manufacturers offering fuel-saving, low-rolling-resistance tires. Make sure you work with your tire dealer to find a quality tire that offers the right features for your needs, vehicle, and budget.

While we are on the subject fuel economy, remember that proper tire maintenance is essential in getting the best fuel economy, and maximizing the life of your tires. Check tire pressure at least once a month, and keep the pressure at the level recommended by your vehicle’s manufacturer. Scheduled maintenance checks on balance and alignment will also help you get the best mileage and optimum performance life from your tires.

Decoding Tire Code: Load Index, Speed Rating, and M+S Designation

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This is the last post in our series on tire code. A uniform tire code is found on most every vehicle tire manufactured. Those who may be shopping for a new set of tires will find a wealth of information in this code to help them determine which type of tire to buy. Our first post focused on the type of tire and section width and the second post looked at aspect ratio, tire construction and wheel diameter. This week, we will examine the rest of  the code.

Performance Index

The tire performance index is displayed after the wheel diameter, and represents the tire’s load and speed ratings. In this case, the 93 load index represents 1,433 pounds, and the speed rating of V represents 149 mph.

Common Speed Ratings

Letter

L

M

N

P

Q

R

S

T

U

H

V
Max. MPH

75

81

87

93

99

106

112

118

124

130

149

All-Season Tires with Mud and Snow Designation

When a tire has  M+S on it, that means that it meets the tire has been developed to handle driving in mud and snow. Similar markings for this include MS, M&S, and M/S. .

Why are Load Index and Speed Rating Important?

A tire with the correct tire load index for your vehicle assures you that your tires are made to handle the weight of your vehicle. The speed rating shows the maximum speed your tires can handle, which tends to be more important in countries with roadways that are not subject to speed limitations.

Of course importance of the mud and snow designation will depend on the climate you live and drive in.

With the entire tire code, it is important to stick with your vehicle manufacturer’s recommended specifications to assure safe and optimal tire performance. Remember – choosing  a dependable, quality tire is just the beginning. Your tires must also be developed for the best performance for your specific vehicle.

Decoding Tire Code: Aspect Ratio, Tire Construction, and Wheel Diameter

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Last week, we began a series for those who may be shopping for a new set of tires and need a little more information in determining which type of tires they need.  We began looking at the universal tire code that is found on most every vehicle tire manufactured. Last week we looked at the type of tire and section width. This week, we will get a little further into the code.

Aspect Ratio

The aspect ratio of the tire is listed as a percentage and gives the height of the tire from the bead to the top of the tread. Here the number is 55, which means the tire height is 55% of the section width of 215 millimeters. The height of this tire would be 118.25 millimeters. A lower number indicates a lower tire profile.

Tire Construction

The construction of the tire is identified by the letter following the aspect ratio. The most common designation is R, which stands for radial construction. Other, less common construction types for modern passenger cars may include D for bias ply construction and B for belted tires.

Wheel Diameter

The number following the construction code indicates the size of the wheel that the tire will fit in inches. The example tire would be designed to fit a 17-inch wheel. Tire sizes on most vehicles begin at 13-inches and go up to 18-inches.Custom package wheels can be 22-inches or even larger.

Why are Aspect Ratio, Tire Construction, and Wheel Diameter important?

Aspect ratio is an important sizing calculation in tire fitting, and should be considered with wheel diameter with the best tire and wheel combinations. Lower aspect ratio typically indicates a high performance tire, with better lateral stability. Most of the new tires you encounter will be marked R for radial construction, however if you are replacing old tires, you may see the D or B designations.

As with last week’s part of the code, it is important to select your vehicle manufacturer’s recommended specifications to assure safe and optimal tire performance. While buying a dependable, quality tire is important, it also must be developed for the best performance given the weight and design of your vehicle, so consulting a tire expert is a must.

Next week, we will wrap up decoding tire code by taking a look at Load Index, Speed Rating, and use designation.

 

Decoding Tire Code: Type of Tire and Section Width

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Even though tires may basically look the same, there are a lot of distinct characteristics and features to consider when selecting tires. If you are shopping for a new set of tires, you may be overwhelmed by the choices, and wondering which tires are the right ones for you.  Fortunately there’s  a pretty quick and easy way to gain a lot of information about your vehicle’s tires – just read the tire code on the tire.  You may have noticed the tire code, which is imprinted into the side of the tire, while washing your car or checking your tire pressure.

 

Each section of this alpha-numeric sequence tells you something about the tire. Being able to decode the tire code on your current tires will help you determine the type of replacements you need.

Type of Tire

The type of tire and it’s intended use are indicated by the first letter in the code. Letter designations include P for passenger vehicles, T for temporary spare, LT for light truck metric, C for commercial, and ST for special trailer service.

Section Width

Following the tire type letter is the section width of the tire, which is listed in millimeters. This is the widest point from sidewall-to-sidewall, so a larger number indicates a wider tire. In this case, the tire has a width of 215 millimeters.

Why are Tire Type and Section Width important?

The correct size and tire type are necessary to assure safe and optimal tire performance. Selecting a quality tire will not assure the best performance if the tire is not made to accommodate the weight and design of your vehicle. Additionally, tire size is a factor in the calculations of the computerized functions of today’s vehicles. To assure accuracy, it is important to hold to the recommended tire size.

Next week, we will continue to decode tire code by taking a look at Aspect Ratio, Tire Construction, and Wheel Diameter.

Run Flat Tires – Things to Consider

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Dear Tracy,

I have heard that there is a new type of tire, called a run flat tire, that prevents blow outs. I recently had a blow out that scared me so badly, I almost wrecked. Can you tell me more about these tires? I really think I would like to get them!

Cindy W.

Dear Cindy,

You may have just heard about run flat tires, but they have actually been around for awhile. In fact, the idea for a self-supporting tire goes back to the 1930’s when a “bullet-proof” tire was developed for military vehicles and armored cars. This tire featured a sponge rubber inner tube that did not require air and was drivable, even after taking several bullets. (Tire history fans can read more in this 1935 article found in Popular Mechanics.)

Today’s run flat or zero pressure tires are designed to resist the unstable effects of deflation when punctured, and allow the vehicle to continue to be driven at a reduced speed for a limited distance, usually up to 100 miles. Run flat tires do not “prevent” blow outs, but they do keep your car more stable and drivable in the event of a flat. While these are good features, there are some draw backs to consider:

  • Run flat tires have much stiffer sidewalls so they are able to maintain vehicle weight. The result is compromised ride comfort.
  • The reinforcements necessary in run flat tires add weight to each tire. The heavier weight compromises vehicle handling.
  • Run flat tires may cost up to twice as much as standard tires. Some reports also suggest that they have a shorter life-span.
  • Drivers must pay close attention to tire pressure as pressure loss is harder to detect with run flat tires. While the use of a tire pressure monitoring systems (TPMS) can provide low pressure warnings, if those warnings are ignored, tire damage and destabilization may still occur.

Some vehicle manufacturers are designing vehicles to be equipped with run flat tires and engineering ways to offset these drawbacks. The good news is that as car manufacturers move in this direction, the technology behind the run flat design should continue to improve. One day, tires that prevent the type of experience you had may be the new standard.

Studded or Studless Winter Tires?

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Dear Tracy,

I have been hearing about studded tires and how they are best for driving on snow and ice. Is this just another name for winter tires or are they something all together different?

Jean A.

Dear Jean,

While studded tires are for winter driving, not all winter tires are studded tires. Studded tires feature a series of metal studs, which are built right into the tire tread. These studs are designed to penetrate snow and slush,  and grip into ice that lies beneath. Winter tires without studs, or studless tires feature a softer rubber than all season tires, which is intended to provide better gripping. The open tread design is another feature that gives winter tires better handling capability on slush and snow.

Like tire chains, the problem with studded tires is that if the studs are not digging into snow and ice, they are digging into the road surface. This is why studded tires are not allowed many areas. Typically if studded tires are permitted, it is only for specified times during the year. While studded tires do offer handling advantages such as better cornering ability, increased traction and more powerful braking force on snow and ice, they can actually cause a poorer handling on non-icy roads due to increased friction. Unless you are an ice road trucker, you are probably better off with studless winter tires.

Rolling Resistance & Fuel Economy

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Dear Tracy,

I know that I am going to need to replace my tires soon and am currently doing research on my options. Can you tell me how important a factor “rolling resistance” is when selecting tires? Is this a crucial feature in getting the best fuel economy with my car?

Adam S.

Dear Adam,

Rolling resistance refers to the force resisting motion when the tire moves along the surface of the road. The rolling resistance of a vehicle’s tires definitely does have an impact on its fuel economy. In fact, most vehicle manufacturers specify original equipment tires with low rolling resistance to optimize performance for government Corporate Average Fuel Economy (CAFE) mandate testing. These tires are usually designed for lower weight and rolling resistance, and can be constructed with thinner sidewalls and shallower tread depths. Even the tire’s chemistry may have an impact of rolling resistance. While good for fuel economy, these tires may not have all the attributes you would want in your replacement tires.

Fuel economy is one of many tire buying considerations you should think about in selecting a set of replacement tires. The type of tire you select should offer both performance and safety for your particular car, the type of driving you do, and for the climate in which you live and drive. Many of today’s major tire manufacturers are now offering fuel-saving, low-rolling-resistance tires. Make sure you work with your tire dealer to find a quality tire that offers a good balance of the features and benefits that are important to you.

Finally, when striving for the best fuel economy, remember that your tire selection is just the beginning. Proper tire maintenance is essential not only in getting the best fuel economy, but also making the most of your tire investment. Monitor your tire pressure at least monthly, and keep the pressure level at the amount recommended by the vehicle manufacturer. The correct pressure will be listed in your owner’s manual or labeled on the driver side doorjamb. Regular checks on balance and alignment will also help to make sure you get the best mileage and longest performance life from your tires.