The way the story goes, technicians from the Goodyear Tire & Rubber Co. surreptitiously descended upon a parking lot in Ohio a few years back, wandered among the parked cars and took tire pressure samples.

They discovered that some 60 per cent of cars tested had incorrect tire pressure or were shod with tires past their service life. The thing is, the cars all belonged to Goodyear workers -- it was the employee parking lot.

If you were to do the same thing in a lot full of motorcycles, you'd probably have the same results. Despite the huge risks associated with riding on incorrectly inflated or worn out rubber, a lot of riders just don't give it much thought.

Big mistake. Despite what many riders think, there isn't a lot of difference between car and motorcycle tires in terms of basic makeup.

There are different rubber compounds for different applications, but the vast majority of bikes run on tires with the same kind of bias ply construction as cars and trucks. That said, radial tires are becoming more popular, especially with hard-riding sport bike enthusiasts.

What separates car and bike tires is shape.

Cars and trucks steer by means of slip angle changes, but motorcycles are steered primarily by camber changes, more commonly known as lean angle. Because of this, motorcycle tires are designed with much more rounded profiles in order to facilitate the changes in lean angle.

"A motorcycle tire's contact patch is constantly changing with the bike's lean angle, moving from one edge of the tread to the other, often instantaneously," says Bernard Jarrousse, product and marketing manager for tire-maker Michelin North America. The contact patch is also much smaller on a bike tire, a by-product of its rounder profile.

"Don't expect to get the mileage from your motorcycle tires that you would from your car tires," Jarrousse says. "A car gets much of its cornering stability from the mere fact that it has four wheels. A bike, on the other hand, relies almost entirely on the adhesion of its tires' rubber compound to go around corners safely.

"Because of this, motorcycle tires have to be made with softer rubber compounds, which naturally wear out faster."

Most manufacturers recommend changing tires after a maximum 32,000 kilometres or so on touring bikes and cruisers and half that on sport bikes, depending on how they're ridden.

Unlike their four-wheeled counterparts, you can't rotate the tires on a bike. The front and rear wheels are sized differently, and subject to different stresses.

"The rear tire transmits the power to the ground," says Bob Graham, motorcycle product manager for tire-maker Bridgestone Corp., "but the front tire handles 95 per cent of the braking pressure.

"Bikes also have significantly more weight transfer than cars and it's mostly from rear to front."

While Dunlop Tire & Rubber Corp. is probably No. 1 in North America, both Bridgestone and Michelin are major players in the motorcycle tire industry.

Bridgestone supplies original equipment tires for most metric cruisers and Japanese bikes in Canada and the United States and Michelin is deeply involved in motorcycle racing. Michelin introduced the first motorcycle radial tire in 1985.

Both Jarrousse and Graham recommend not "cheaping out" when it comes time to buy new rubber.

"Because tires play such a key role in a motorcycle's handling and grip, shopping solely on price is a bad idea," Jarrousse says. "Educate yourself on the differences between various tires offered by each manufacturer.

"In some cases, a single tire company may offer three or four different tires for a specific bike. Your individual riding style and how much you ride will determine which particular tire is right for you."

It's also a good idea to talk with other riders about their experiences with various types of tires, especially guys who own the same model or a bike similar to your own. Internet bulletin boards and discussion groups can be an excellent source of information.

"If you're a hard-charging sport bike rider, you could go through a set of tires in less than 5,000 kilometres," Graham says.

Given the speeds some of today's super bikes can get up to and how quickly they get there, cheap rubber is not a great idea. As well, brakies, wheelies, burnouts and corner-strafing all have a way of consuming tires at a rapid rate.

As far as day-to-day maintenance goes, tire pressure and tire condition should be checked at least once a week, more if you like to rack up the kilometres.

Even a minor drop in tire pressure can have deleterious side effects: Reduced fuel consumption, different cornering stability, inferior high-speed tracking, etc.

All bike tires have wear indicator bars inside the tread pattern. If a tire is near exposing the wear indicator, get it changed immediately.

Above all, keep the rubber side down.