Let's Get Technical: Tires

By Tom Dobush, June 2013

What is the most important part of your car? Give it some thought. Which part is needed in order for all of  the vehicle’s systems to operate to their maximum performance and efficiency? When you whittle it down the answer becomes clear. The engine? No. How about the brakes? Negative. Suspension? Transmission? Nope and nope. All of these systems cannot function properly without tires. After all, the tires are the only part of a car that actually makes contact with the road surface.

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When you take the example to the extreme it becomes easier to understand. For instance look at any type of auto racing these days, tires are always a big talking point. Differences in brand and compound, whether or not to run slicks, intermediates or full on rain tires. When it comes to the last ten laps of any race, the car with the freshest or best managed tires has the advantage. You can have the most powerful engine on the planet, but if you do not have the correct tires to handle all that power, pretty soon you will just be spinning your wheels. Big brakes are great, but are only effective when the tires they are connected to have grip. Suspension and steering are equally connected. Tires are at the root of all of these important systems.

So if tires are the most important part on any car, why are they so often over looked? It is all too common in the auto repair industry to see very nice cars with either neglected, worn out tires or simply the wrong tires.

Discount tire centers are very popular these days as there is a ton of competition in this market segment. Usually good for consumers, competition drives prices down, however in this scenario, it may have pushed prices down too far. Let me explain. Nowadays, many folks allow their price sensitivity to persuade them into saving a few dollars on brand X tires that are cheaper and supposed to last longer. More bang for your buck, right? Not exactly, the rubber that the tires are made of have a maximum shelf life of five years, and sometimes they sit on the shelf for a year or two before they get sold and installed. Many folks purchase high mileage tires that are supposed to last at least fifty thousand miles, but only drive 5-10 thousand miles per year at most. The math doesn’t quite add up. Why not choose tires that have more grip and performance (read: shorter stopping distance, better cornering feedback, i.e. safer) that may only last two years or twenty thousand miles, but increase driving safety and enjoyment dramatically. Over time, the cost differences become negligible, especially since the other systems in your vehicle will be operating more efficiently and therefore wear at a slower pace. If this is true for regular daily drivers, it is only exaggerated further in sports cars and weekend toys. Bottom line: tires are the most important part of your vehicle. Period. Don’t skimp on them.

Now that we’ve established that fact, the next point of discussion is how we approach taking care of our tires. Let’s talk tire pressures. There are many schools of thought here and we could discuss this all day but the basics are all you really need to know. Every vehicle has a factory recommendation for correct tire pressures, usually located in the owners’ manual, on a sticker in the door jam, trunk or deck lid or in some cases on the gas flap. Do you know what your factory recommended specification for cold tire pressures is? Most drivers do not. If you do, good for you, you are ahead of the game. If not, find out. An under inflated tire not only wears out more quickly and unevenly but most importantly is a very common and huge safety risk!

Do yourself a favor next time you fill up your gas tank and purchase yourself a stick or pen type tire pressure gauge for a dollar or two and keep it in your glove box or tool kit. Tire pressures should be checked at least once a month at the very minimum. Ideally, you want to check it every time you drive it, just like we would with a race car. This might not be practical or realistic everyday so a fair compromise is once every week to two weeks, basically as often as possible, even if you have to ask a technician or gas station attendant to do it for you.  Also make sure you have caps on all of your valve stems, the cap is what actually holds the air inside of the tire, the little shrader valve inside the stem is only for letting air in and out and not intended to keep the air in forever.

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Do not rely on the Tire Pressure Monitoring System (TPMS) if your car is equipped with one. It usually states this right in your owners’ manual, the TPMS is meant to supplement an actual gauge. While these systems are helpful in avoiding driving on a flat tire, most systems are not very accurate and will not alert the driver to a slight tire pressure change, which could cause a tire to wear out prematurely or unevenly.

While we are on the TPMS subject, let me also address over inflation. It seems many folks see a flat tire warning light and add air to the tires to make the warning light go out, unfortunately it is often way too much! The factory specs are very specific to temperature and load, while the tire often has a maximum inflation pressure on the sidewall. This maximum is not equal to the recommended pressure! Tires that are over inflated will wear out just as quickly as under inflated tires and are just as dangerous because of a reduction in the amount of tire that makes contact with the road. Really, you do not want to be off from the factory specs by +/- 2 psi!

The next order of business concerning proper tire usage, wear and safety is your car’s suspension health and alignment. The state of your suspension and alignment can completely change the character of your vehicle from confident to downright dangerous. Look for more information in the next upcoming article. As always, I greatly appreciate your questions and feedback and can be easily reached at BavarianRocketScience@gmail.com. Thanks for reading and happy motoring!