Are you one of the people who rate buying new tires right up there with rounding up the cat so you can bring him to the vet? Or do you view it as an opportunity to prolong your enjoyment of your car or truck, ensure its safe riding, get the best quality your budget can afford, and perhaps learn a thing or two along the way? If you belong to the first group, don’t despair, there’s no barrier to membership in the second. Admission is free. All you have to know is where you live.
Rubber and Climate
When deciding on the right cooper tires for your vehicle, size and width should be the first two considerations. The third is the climate where you do your most driving. This will decide the type of rubber your tires should be made of. If you live in a cold climate that gets a lot of snow, you want to look at winter tires since their soft rubber composition will give them a better grip on slippery roads and this translates to better traction when driving in the snow.
Conversely, tires made of more rigid rubber are best if you live in a place where warm temperatures dominate since they will last longer when driven on warm roads, when, as the cliché says, the pavement is hot enough to fry an egg. And if you live in a true four-season climate, you’ll want to look at all-weather tires.
About Those Numbers
The numbers and letters on the sides of your tires should match those on the label found on the door jamb or in the glove compartment. They will cease looking like a secret code as soon as you understand what they mean. The first step is getting down on your hands and needs and finding them.
The first figures we will see are three numbers. Let’s say 235. This is the width. These tires are 235 millimeters wide if you measure from sidewall to sidewall.
Next, you will find a slash followed by 2 digits, such as 45. This is the aspect ratio which is best explained as the ratio of the height of the tire’s cross-section to its width. So, if your tire reads 235/45 it means its sidewall is 45% as tall as it is wide. Another way to look at this is the bigger the aspect ratio, the wider the tire, which means it will grip a wider patch of pavement, thus affecting its handling.
If you see an R following the aspect ratio as in 235/45R, it means you have radial tires, which means the ply cords (layers of the tire’s walls) run radially (at a 90-degree angle) from their centerlines to their beads. The alternative to radial tires is bias-ply tires which have ply cords running diagonally across the walls rather than perpendicularly. Each has its pros and cons.
And lastly, the number following the aspect ratio is the diameter of the tire in inches. This is important since it needs to be the same diameter as the wheel on which it will be mounted. A 234/45R/18 tire will not fit on a 17-inch wheel/
What if You Want a Different Size Tire?
If you want to change tire sizes either because it’s a matter of expense, handling ability, or cosmetic preference, you can – within limits. In passenger vehicles, especially sedans, you need to make sure the change won’t interfere with the clearance between the suspension components and the fenders.
Another thing to check for is that the combined diameter of the tires matches the diameter of your wheels. Your car was designed to roll on tires that fit the specifications of the original set, so failing to adhere to these specifications will not only affect its handling ability, it may lead to mechanical problems. In addition, incorrectly sized tires will throw off your speedometer and odometer readings and even affect anti-lock brakes.
And of course, you need to replace all the tires rather than mix and match. But then it’s always advisable to replace all five tires whenever your car needs new tires.
