Plus-size tires: When more is less
Plus-size tires: When more is less
Larger wheels and tires have taken the fast lane, from street racing to showroom. Tire wheels sized 16- to 18-inch are common place on new vehicles leaving the factory. Older cars still on the road today typically came equipped with 14 and 15 inch tires.
The big-wheeled look has also grown into a significant aftermarket business for tire dealers as drivers increase wheel diameter anywhere from 1 to 8 inches or more beyond the originals—known as plus-sizing.
Style is fueling most of that growth. But retailers also point to more cornering grip and handling. The larger the wheel, the shorter the tire's sidewall and the wider its tread must be to maintain the same outside tire diameter and prevent reducing the tire's load-carrying capacity. The shorter and wider the tire, the better the handling and cornering grip.
Some plus-size wheels and tires live up to their image. Our tests of plus-one, plus-two, and plus-three wheels with common-model tires show that increasing wheel diameter 1 inch—or one plus size—offers the greatest benefit in overall performance. After that, you're likely to pay for small gains in grip and handling with big losses in ride comfort, hydroplaning resistance, and snow traction.
You may also pay more than you bargained for at the counter: Figure on at least $1,000 for four plus-one wheels and tires for a car and $5,000 or more for the largest plus sizes sold for SUVs and pickups.
Plus-sizing brings additional risks for those trucks, since grippier tires that respond more quickly to the steering wheel may increase the chance of a rollover (see Special risks for SUVs below). That's why we don't recommend it for those vehicles unless it's offered as a factory option.Wheels that fitThe offset between the wheel centerline and mounting area is just one of the specs that determine which wheels and tires fit your vehicle.
Plus-sizing isn't for everyone. If you like the way your vehicle rides and handles, stick with the size and type of tires that came with it.
Will plus-sizing pay off? and the color-keyed graphs in What you gain and lose detail what you're likely to gain and lose as you size up. Here's what to think about if you determine that the style and performance of plus-sizing are worth the compromises and costs:
Consider all the risks. You may not care about snow traction if you live in the Sunbelt and drive mostly on dry roads. That's where the wider footprint and stiffer, shorter sidewalls of large plus-size tires perform best. But driving through puddles is more treacherous wherever you live. That's a compelling reason to choose the plus size closest to the original wheel and tire size, which offers the most performance gain with the fewest sacrifices.
Increased risk of damage from potholes and curbs is another consideration. Besides compromising ride, shorter sidewalls provide less cushioning for wheels and tires. Our pothole test bent the plus-two and plus-three wheels on our BMW 5-Series and damaged the wheel and tire on our plus-two-equipped Honda Accord.
Get the right tire size. A car or tire dealer can tell you the proper plus sizes for your car based on its original tire size.
A rule of thumb: Increase tire width by 10 millimeters and decrease sidewall height by 5 to 10 percent for each 1-inch increase in wheel diameter. And make sure speed and load rating of new tires is at least as high as on the factory originals.