Countless people spend hundreds or even thousands of dollars to get larger wheels and tires.

While eye-catching, they're best when the car is parked or at extremely high speeds. In normal driving, you'll notice they:

The promise of greater performance is seldom realized by most drivers, especially when the larger wheel and tire is an option. (In these cases, the suspension system is often optimized for the standard wheel size).

Our philosophy: changing the type of tire does more for performance than changing tire wheel and tire size.

Not convinced by the bullet point list? The following exhibits go into greater detail.

Exhibit A

“Round black things, made of synthetic rubber? Yes. Likely to be broader of tread and shallower of sidewall if fitted to a rapid car that has lots of roadholding? Yes. It makes the car look better, more like a track racer. But let’s get our priorities right.

A wide tyre looks good, of course. But it’s wide so that more rubber can touch the road, which means more grip. This sounds obvious, but it’s not a linear relationship if width against roadholding against driving pleasure. A certain amount of weight per unit of tread area is needed to ensure reliable grip when the road surface is slippery, and too much lightly-laden width also causes the tyre’s contact patch to be the wrong shape.

If that patch is wider than it is long, there’s less self-aligning force acting on the wheel as it rotates. This reduces both the steering’s self-centering and the driver’s awareness of when a slip-angle is building up (the angle of a wheel relative to its direction of travel) -- in simple terms, the feel of how much grip is left. A short, wide contact patch can also lead to tramlining over ridges in the road, because there are greater leverages acting on the tyre’s shoulders owing to their greater distance from the steering axis, and there’s less force to pull the tyre straight.

Relatively narrow tyres with flexible sidewalls give the best ride comfort and the broadest, if not the crispest, range of steering feel. Wide tyres with stiff sidewalls give more precise reactions, but a narrower window between full grip and a visit to the hedge...”

"Looks... will always be a potent lure. BMW’s [E36] M3 has wide, very low profile tires because the marketing department decreed it. So, in order to ride decently, it has lots of compliance in its suspension which spoils the sharpness. Back to square one."

-- CAR Magazine, Dec 1997

Exhibit B

"Only an extreme Luddite wouldn't agree that today's cars are better than they have ever been. Advances in every area of technology and design have made improvements and devised innovations that weren't even dreamed of by our automotive forefathers. Cars are aerodynamic and fuel efficient. They're comfortable and environmentally friendly, have much higher grip and corner better than all-out racing cars from just a few years ago. And even if the cars of 50 and 60 years ago were more stylish -- a subjective call -- the latest retro trend is bringing some of that look back to wrap up a modern package. If this were a perfect world, that could be the end of the story, But like our world, progress isn't perfect. Even when it results in dramatic improvements, progress always leaves something behind.

Years ago, all cars had tall, skinny tires. These tires had round cross-sections that resulted in a tire footprint on the ground that was longer than it was wide. This footprint shape was highly effective at holding a straight line: any small motion away from center would create a self-aligning torque that pulled a tire straight again. To move it away from straight ahead required significant effort at the steering wheel to overcome this self-aligning torque. To a driver, this directional stability meant a car was easy to drive at high speeds. A good car would track accurately and allow a nicely progressive buildup of steering effort to deflect it away from a straight path. Early radial tires with highly rounded crowns from European tire makers -- like Dunlop, Michelin and Pirelli -- were especially appreciated for this characteristic.

Sports-car builders such as Jaguar, Mercedes-Benz, Ferrari and Aston Martin knew how to take advantage of directional stability to create cars with legendary steering feel. Even lower-cost sports cars like the MGB or Austin Healey 3000 exhibited wonderfully precise high-speed road manners. Engineers from Saab, Volvo and BMW understood the concepts and applied them to the sedans that are now remembered for their steering excellence.

It all began to change in the 1970s. Racing cars had moved away from tires with tread grooves to slick tires. Because of extremely high levels of horsepower, these tires needed to be very wide to provide driving traction. Racing cars have highly adjustable suspensions, so wide tires could be used on the front wheels and the alignment set to take advantage of the performance levels.

Racing cars of this and almost every other period are designed to operate strictly at their limits of performance. Most are not very pleasant to operate when driven slowly. Everything is sacrificed for predictable performance at the tire's limits. Racing cars dart and weave and seem uncoordinated at low speeds and only settle down as their limits are approached.

This is the opposite of what one wants in a street-driven car, especially a sports car. But because the racing look included wide tires and flared fenders, the street-performance market developed along the same lines. Enthusiasts fell for the idea that wide tires were better for handing and performance.

In fact, they aren't. As a tire gets wider, its contact footprint gets shorter, leaving less opportunity for a build-up of self-aligning torque. In addition, wide tires need to stay square to the ground to produce maximum cornering. This can be accomplished with a highly adjustable suspension on a racing car with little suspension travel, but its nearly impossible to attain on a car that must absorb bumps and potholes on the street.

None of that mattered: Style dictated fat tires no matter how they might adversely effect handling. Paradoxically, the usually poor result of placing excessively wide tires on inappropriate street-driven performance cars soon was accepted as part of the character of high performance driving. Cars with skinny tires and superb steering, such as the mid-1980s Mercedes-Benz 300E Sedans, lost their edge, wandered at high speed and became darty at low speeds with the application of wide performance tires. The ultimate levels of grip on a racetrack might have been higher, but the handling characteristics when driven on the street suffered.

By the late 1980s, car manufacturers were following the lead of the aftermarket by offering wide tires on their performance models. Engineers at tire companies and car manufacturers struggled to find suspension setups that would give back what had been lost in steering feel and directional stability. Some, like BMW and Porsche, were more successful than most, but their efforts were still not up to even fairly average cars of previous decades. Meanwhile, power steering became popular, even on sports sedans, and proper steering feel was relegated to distant memories.

Today, although suspension systems have been refined to take better advantage of wider tires, the trend has been to larger wheel diameters with lower aspect ratios (the ratio of a tire sidewall height to the overall tire diameter). So even though the wheels are getting bigger in diameter, lower aspect ratios mean the overall diameter is staying the same. Fine on the racetrack where ultimate grip is king, but in the street the end result of this misdirected technology is even shorter tire contact footprints that further degrade steering feel and directional stability.

For street usage, tires of 17, 18- or even 20-in, wheel diameters are actually detrimental to good handling, yet enthusiasts demand them, tire manufacturers produce them and car makers put them on sport models and show cars that represent the extreme edge of vehicle performance. It's a fantasy based upon how fat, low-aspect ratio tires look under bulging wheel wells rather than actual vehicle dynamics.

Unfortunately, the trend shows every sign of continuing. First, the gradual deterioration of steering quality means only a small number of today's automotive engineers have ever experienced how good it can be. They look perplexed when you complain about something they have just been praising. Second, the look most performance stylists are emulating is still based upon racing, mostly touring sedans from Europe and Asia. These racers use ultra-low profile 17- and 18-in. tires, so hot street cars must require the same size rubber.

Lastly, it is clear that technological progress has made the modern automobile a remarkable device, so anyone who suggests otherwise is someone who will soon be left behind."

-- "Where Has All the Steering Gone?" by Kevin Clemens, European Car

Exhibit C

More often than not, the tires included with larger wheels do not have the "Mud & Snow" rating signifying they are designed for 'all-season' use. The rubber of these tires becomes slippery at low temperatures on dry surfaces, and their wide tread blocks struggle to find traction in the snow. Not convinced? See Patrick Bedard's column "The Tires of Summer Just Say No to Winter".

Exhibit D

The 'L-Tuned' version of the Lexus IS300 has 225/40R18 Michelin Pilot Sport tires, a supposed 'upgrade' from the stock 215/45R17s. Yet in a September 2002 test, Motor Trend found "The Michelin tires' added width (and assumed added grip) didn't translate directly into improved slalom speeds. A stock IS300 posted slightly better speeds through the cones."

Exhibit E

From Michelin's website: "Tires are part of your suspension, using lower profile tires is like using shorter, stiffer springs."

Exhibit F

One visitor writes: "I read with great interest your article on big wheels - or more specifically why you do not recommend them. I am in the process of putting together a wheel and tire guide for The Toyota MR2 Drivers' Club here in the UK. When I started out, I thought sound information would be easy to come by and that big wheels were good. What I have found though is that there is a minefield of misleading information (e.g. "fit bigger wheels to increase performance" - period, no qualifying statement!), and that the chassis engineer has already selected the optimum size wheels."

Exhibit G

When David Jordanger of Dealer Tire recently spoke at a quarterly meeting for one of the local car clubs, we were happy to hear him correct the common misconception that a bigger tire 'puts more rubber on the road'. As he said, "A bigger, wider tire will change the shape of the footprint on the road but not make it bigger or smaller. The footprint area is more or less defined by dividing the air pressure in the tire into the weight it is carrying."

Exhibit H

This page on Michelin's website is worth reading.