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How to Buy Car Tires

After living in the city for 30 years, EC moved to the countryside. He writes about life in the mountains, dogs, plants, and cooking.

Treads on Tire (Photo courtesy by LDB Photography from Flickr)

Treads on Tire (Photo courtesy by LDB Photography from Flickr)

Buying Car Tires Can Be Easy

Without a set of good tires, your car will not run smoothly, and your engine will use more gas than it should. Your safety will also be at risk if you're using the wrong tires for your car.

Here are four important factors that should be considered when you're buying car tires:

  • Know your tire size. This information will save you time on buying tires.
  • Determine the type of driving you do. Your car tires must fit all your driving needs: best or worst. Types of tires may include all-season tires, winter tires, and many more.
  • Get expert advice from an authorized tire dealer. Don't forget to bring your warranty booklet and DOT registration card, if you have any. These should be included with every tire purchase. For warranty and safety issues, always complete the DOT tire registration form.
  • Learn the age of the tire you're buying. Look for the expiration date.
Cadillac Front End (Photo courtesy by oceanaris from Flickr)

Cadillac Front End (Photo courtesy by oceanaris from Flickr)

How to Know Your Tire Size

The original size of your car tire is included in the owner's manual, or on the tire placard attached on the driver's door jamb, or on the glove compartment door, or inside the fuel hatch. You may also find the current tire's designation on the ‘sidewall.' These are the numbers and letters on the sides of the tires. It will be useful to learn reading a sidewall.

Using the size tire that the manufacturer of your vehicle suggests is best because the tires of the wrong size will not fit your car. If you want to change the size, width, aspect ratio, and even the wheel diameter, you must consider a lot of things before making the final decision.

Tire Width

Tire width refers to how wide or how narrow is the tire. Having a wider tire will give the car a better grip on dry pavement; however, the gas mileage will be worse. Also, too much width may cause damage due to tires chafing against the car's body. Narrow tires have good traction during winter but too narrow can put your safety at higher risk. There should always be enough rubber touching the road for the car to keep going.

Aspect Ratio

The aspect ratio affects the height of the tire, how high the sidewall is. A low sidewall tends to be stiff, so that cornering is improved, but your ride may be a little rough. Also, too much change in the aspect ratio can confuse the speedometer so you will not know how fast you're driving. If you really wanted to have both—reliable cornering and accurate speed reading—you should try the ‘Plus-One' set-up and buy new wheels. This will allow you to change your tire size and width without messing up the speedometer of your car.

Wheel Diameter

Wheel diameter is a bit difficult to change. 16-inch wheels will always require 16-inch tires. You will get different wheel diameter when you buy new wheels, especially if you'd be using the Plus-One set-up. Note: there are also set-up formulas for Plus-Two, Plus-Three, and so on.

Tips on Buying Tires

Purchase the tires with the same brand, size, and design. Call around to save time and money. Tire retailers will ask for exact information, which you will find printed on each tire. Here's the code:

  • ‘P' (means passenger vehicle),
  • then the tire width (in millimeters),
  • the height is shown as a ratio to the width,
  • ‘R' (means radial),
  • and wheel diameter is the last number.

The bigger the wheel diameter, the lower the aspect ratio. Find out the particular tire size when the wheel diameter is increased by an inch or so. Use this calculator to get the correct conversion on plus sizing.

Aspect ratio is the reason why a Porsche has wheels that looks like a band of rubber is wrapped around the rim, and a Cadillac has tires that look like a big bubble.

Close-Up Porsche Tire (Photo courtesy by Rockies from Flickr)

Close-Up Porsche Tire (Photo courtesy by Rockies from Flickr)

Close-Up Cadillac Tire (Photo courtesy by Nick Venables from Flickr)

Close-Up Cadillac Tire (Photo courtesy by Nick Venables from Flickr)

Tires for Sale in the Supermarket (Photo courtesy by brooy from Flickr)

Tires for Sale in the Supermarket (Photo courtesy by brooy from Flickr)

How to Get a Good Deal on Tires

There are a lot of quality tires offered in the market, so it is wise to do a bit of research first before rushing to the nearest tire store. Look at the markings on the sides of your car tire. These may look nonsense to you but understanding the numbers and letters will help you choose the right tires for your car and save money at the same time.

The categories of tire information squeezed and stamped onto the side of each tire are as follows:

  • Tread Wear and Traction Ratings
  • Load and Pressure Limits
  • Vehicle Application
  • DOT Codes
  • Tire Width
  • Aspect Ratio
  • Radial Designation
  • Wheel Diameter
  • Load Index
  • Speed Rating
  • Ply Construction

Tire Size

Includes the width, aspect ratio, and wheel diameter. The numbers will be the same in all brands of tire.

Treadwear and Traction Ratings

A higher rate will give you more miles to drive and has advantageous gas mileage because the rubber is a bit harder, but will have inferior performance on cornering. So if your kind of driving involved lots of cornering, do not choose higher treadwear ratings. A higher dry traction rating is recommended.

Load and Pressure Limits

Load and pressure limits are not so important—unless your vehicle is a truck that you're using to haul heavy loads. The tire with a higher maximum tire pressure has less resistance and better gas mileage.

Speed Rating

This may be important if you're driving at the speed of 120 mph and above. Normally, the average speed rating for tire will suit the average driver fine.

Tire Diagram (Photo courtesy by Matt Wright from

Tire Diagram (Photo courtesy by Matt Wright from

Flat Car Tire (Photo courtesy by lissalou66 from Flickr)

Flat Car Tire (Photo courtesy by lissalou66 from Flickr)

Low-Budget Tire Purchase

Need tires but low on cash? Here are some tips on how to buy tires on a limited budget:

  • Save money on buying used tires. Just inspect each tire meticulously. Make sure that every tire you buy is not too worn out. The downside here is you may not find four tires of the same brand, but this will be all right as long as they are only temporary.
  • Call different tire retailers. Make a comparison of their asking price both on used and new tires. Choose the dealer that offers free installation of tires.
  • You must always consider installation and shipping charges if you're planning to buy tires online. This way, you'll know if the bargain deals you found are really good.
  • You may buy two brand new tires at first, instead of buying all four. Have the new tires installed on the rear axle to help prevent the car from fishtailing or hydroplaning on wet roads.

New cars are sensitive to tires with different degrees of wear; so rotate the tires to keep the wear even. This will mean buying new tires at the same time so keep regular check-up on tread depth. Tread with a minimum of 1/16th of an inch thick is safe.

Tire Blowout (Photo courtesy by chantastic from Flickr)

Tire Blowout (Photo courtesy by chantastic from Flickr)

When Is the Right Time to Buy Tires?

Most auto manufacturers recommend changing your car tires when they are six years old, and the spare tire included even if you've never used it. According to research, old tires become road hazards.

Passenger car tires usually last 44,000 miles, so these tires should be replaced before the 6th year of age unless the tire blows or busts. Many people take for granted that unused spare tires will remain durable even after ten years.

Scientific research shows that oxygen migrating through the covering of the tire changes the chemistry of the rubber and weakens the internal structure of the tire, often resulting in tire failure.

How to Find the Age of a Tire

Locate the letters ‘DOT' on the sidewall; then look for the serial number - a combination of 12 numbers and letters. The last numbers identify the week and year of manufacture. Example: 2608 means 26th week of the year 2008.

How to Buy Tires for a Go-Kart

Tires for go-karts usually have bigger sizes at the rear. Tires with ribs have better traction than the bubbly type.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.