Tips on Tire Codes and Tire Maintenance

Most drivers hardly ever give them a thought until it’s time to change a flat, but tire maintenance is one of the most important things you can do for your car in terms of ensuring safety, economy, and comfort. Sure, the engine won’t start if something goes missing under the hood, but even when it isn’t running, the tires are still exposed to dangerous conditions. Even those who have no interest in changing their own oil should be aware of some basic automobile tire maintenance facts.

The first order of business is to become intimately acquainted with your tires. Get to know them personally. In other words, if you had to go into a tire store and buy a new tire would you know what to ask for? There’s really no excuse for not knowing this key component of tire maintenance since all the information you need is printed right there in front of you. Every automobile tire comes equipped with a code printed on the sidewall that provides you with all the information you need to know. The tire codes begin with a letter or letter combination.

P stands for passenger car.
LT stands for light truck.
ST stands for special trailer.
T stands for temporary.

After the letter or letters there will be a number, for instance P215. This number tells the width of the tire in millimeters and is measured from sidewall edge to sidewall edge. After this number you’ll see a slash mark and another number, for instance P215/65. That number is the ratio of the tire’s height to the tire’s width. That number will be followed by a letter.

B means it has a bias belt.
D means it has a diagonal bias.
R means it is a radial tire.

Following that letter there will be yet another number. (Tire codes can be a nightmare for those with numeral dyslexia, can’t it?) This number indicates the measure of the diameter of the rim that the tire is built to fit and it will be in inches. So you will see something similar to this on a tire: P215/65R15. Then there will be space before you’ll see the second of the two tire codes. This code will begin with a number such 90 that indicates the load index, followed by a letter that represents the speed index. The load index number multiplied by four is considered the maximum weight that the tire can be expected to carry, including passengers and cargo. The speed index indicates the tire’s speed capability. This number has been determined through testing, but remember to keep in mind that these measurements of load and speed are meant to be used in connection with tires that are kept at recommended inflation. If your tires are overinflated or underinflated, that presents a whole other story.

Which brings us to the safety component of tire maintenance. Driving a car with underinflated tires can be more dangeorus than you probably think. Lack of proper inflation can lead to difficulties with steering and less than stellar handling. Most people on the road at this very minute are driving with at least one tire that is lower on air than it should be. Underinflation is very easy thing to overlook, but it’s even easier to fix. Just buy an accurate tire gauge and check them at least once a month. Mornings are the ideal time to check tire pressure because the more you drive, the more the tire heats up, causing expansion of the air inside, leading to readings that may be slightly off.

Of course, tire maintenance means more work that simply checking air pressure; you should also consider having them rotated on a regular basis. While tire rotation used to be considered a necessity, debate is rising as to whether the expense is worth the return on contemporary tires. Those who question its value suggest that as long your automobile remains in proper alignment, tire rotation is no longer really necessary. Of course, if rotation is covered under your warranty, there’s absolutely no reason not to take advantage of it.

Finally, in these days of ever-rising gas prices, regular tire maintenance can also save you money. Understanding the meaning of the tire codes is the first step; unless you know what kind of tires you’ve got you can really do anything else. Riding on subpar tires has a definite effect on the gas mileage you can get, so you should really take notice of those rubber disks each time you climb in. Every penny counts nowadays.


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