Size matters when it comes to replacement tires

Side view of black car

Most of us tend to buy replacement tires for our cars based on brand recognition, price, size, looks or some combination of the four.

There is really a lot more to consider. I call it the Zen of tire-buying.

Think of it this way: All of the technology, engineering and performance packed into the design and price of your car are realized through four small contact patches, or footprints, where your tires meet the pavement.

Whether it's a $128,000 Audi R8 or a $17,000 Chevy Cruze, tires are the final arbiter of how a vehicle performs.

The replacement tire we choose will influence ride quality, handling and fuel economy to a certain degree.

If none of that matters to you, by all means buy your next set of tires based on low price or name brand.

But understand that when a car manufacturer engineers a vehicle, it invests time and money determining the ideal wheel size and tire type, often working hand-in-hand with a tire manufacturer to devise an all-new tire and tread design to maximize the vehicle's handling dynamics and fuel economy.

Rolling resistance is the key contribution tires make to fuel economy.

Highway fuel economy is generally better than city fuel economy because it takes less fuel to keep a car's wheels turning than it does to get them rolling when the light goes green.

In either event, tires with less rolling resistance produce better fuel economy. Tires made of harder material roll more easily than those made of softer material. A more pronounced tread design produces more rolling resistance than a subtle tread design.

Replacing regular tires with low-profile ones is an easy way to make a car look sportier, but doing so can have consequences.

A shorter sidewall reduces the tire's load capacity.

To maintain the load capacity, every inch lost in sidewall height needs to be compensated for with an additional inch in width. That is, the low-profile replacement tire must be wider than the original-equipment tire.

You can avoid doing the shorter-wider math simply by comparing the replacement tire's load capacity printed on its sidewall to the original-equipment tire being replaced. They should be the same.

Just because all tires are black doesn't mean they are interchangeable. The right replacement tire can make a big difference in performance and fuel economy.

You can follow on Twitter and Facebook.