Dear Car Talk:
A buddy of mine just bought a new Lexus ES 350, and he ordered it with 19-inch wheels. Is there an advantage to having larger wheels on a car? --Wayne
Well, most people think they look cooler. I think that's the prime motivating factor.
They do also improve handling. Generally speaking, the opening for the wheel-and-tire combination (the wheel well) is only so large. So when you use a larger wheel, you usually pair it with a tire that has a shorter sidewall.
Tires with short sidewalls are called "low-profile" tires. And when you turn, those low-profile tires have less sidewall that can flex. That makes the car's turning response a little sharper.
So if you have a car that's not known for its sharp handling -- like a Lexus ES 350, or a Lincoln Navigator -- you can improve the handling a bit by getting larger wheels and having sidewalls that flex less.
The downside is that those low-profile tires degrade your ride quality. All that extra sidewall, with its greater flexibility, helps soak up bumps and road imperfections, which softens your ride. So it's a trade-off.
Now, on a car that is designed to have a very soft ride, like the Lexus ES, you might have room to accept a slightly firmer ride in exchange for better handling. It's likely the ride still will be pretty darned comfortable.
But on cars that already have firm rides, you'd probably be better off going for the standard wheel size with the larger-sidewall tires.
The other downside of tires with short sidewalls is that it's easier for the tire and the wheel to get damaged by potholes or curb stones that you drive over.
And if you think those optional 19-inch wheels were expensive when you bought the car, wait until you start having to replace them along with your 19-inch tires.