The heavy duty truck market discovered in the late '80s what "air ride" could do for the comfort and controllability of all manner of trucks. "Air ride" of course, is a euphemism for air springs - replacing conventional coil and/or leaf springs with pneumatically operated "springs."

Air spring installations penetrated deeply and quickly into the heavy-duty truck market, but Firestone Industrial Products Co., the leading maker of air-ride components, says it wants to dramatically expand the application of air springs in the light-truck and sport/utility vehicle (SUV) segments.

Currently, just 2% of the light-truck and SUV market rides on air suspensions. Firestone predicts that will increase to 10% by 2003 and 40% by 2008.

"We're going to create the future," says Paul R. Mineart, president of Firestone Industrial Products, about his plans to create a "pull-through" demand for air suspension applications via the aftermarket. "Sooner or later the OEs are going to wake up."

Heavy-duty truck and trailer manufacturers already have heard the alarm clock ring.

The North American truck air suspension market is expected to reach 85% by 2003. It's already at 81%, up from just 50% in 1988. Almost 70% of trailers ride on air suspensions, up from 15% a decade ago. That market is expected to hit 82% by 2003. Europe is on much the same growth curve.

Firestone Industrial says conventional light-truck/SUV leaf and coil suspensions can't offer the sophisticated ride and handling today's sophisticated customers crave. Set up conventional steel springs and leafs stiffly and you get a good ride when the vehicle carries a heavy load, but without a heavy payload to compress the springs, the truck bucks and jumps like that kids' penny-a-ride pony outside the grocery store.

But if you soften up on the spring rates to deliver a quality unloaded ride, there's no suspension compliance when the vehicle is weighed down.

Air springs, as you've probably already guessed, can deliver a great compromise by varying the spring rate according to disparate load characteristics. This, says Firestone, would handsomely benefit the light trucks and SUVs so embraced by today's customers.

Firestone says that it will have to engage in a substantial departure from the air-spring products it provides for heavy duty applications; namely, the light truck/SUV market will require much smaller units that make adaptation of heavy duty air-spring components impractical. And the nature of using compressed air means that smaller components doing the same job must be driven by higher pressures. Higher pressures generally translate to higher cost and lower durability.

Apart from the air spring units themselves - one at each wheel - a system for passenger vehicles also requires a compressor, a height sensor/controller, a compressed-air holding reservoir, air lines and some wiring and most likely some sort of driver-activated dashboard control. Hardly complicated.

Air springs aren't anything new in the passenger-vehicle market. Numerous automakers have offered what broadly can be termed as air-spring suspensions. For passenger cars, the ideal usually has been to provide better load leveling or to enhance handling by adapting the suspension to offset cornering and other dynamic forces acting upon the chassis.

But Firestone sees trucks and SUVs as the "growth" segments for air springs - largely because those vehicles tend to be asked to haul more and heavier loads, not to mention towing - than a typical passenger car. Only a few current high-line SUVs offer air springs: Range Rover, the Lincoln Navigator and Toyota Motor Corp.'s Lexus LX470 come to mind.

The Carmel, IN-based company is endeavoring to drive down air spring product costs, seek supplier partnerships to achieve proprietary positions and focus on research and development the longer-life, high-pressure springs and complete air suspension systems light vehicles will require.

For now, Firestone will use its position in the aftermarket as the springboard to possible OEM business. The company markets three distinct aftermarket air-spring packages: Ride-Rite, Coil-Rite and Sport-Rite.

Ride-Rite is a "helper" system designed for fitment between the frame and the rear leaf springs to assist the regular suspension with load-leveling duties. Ride, handling and reduced maintenance of the regular suspension bits are Firestone's cited benefits.

The Coil-Rites fit inside stock front coil springs to not only assist in load handling but also to provide true variable-rate springing. Firestone encourages teaming Ride-Rite and Coil-Rites together for air-springing at each wheel. Sport-Rite is for occasional load-haulers who want a more controlled ride that also can be adjusted.

Then there are various Level Command kits that bring an onboard air compressor and centralized control of the air springs; add an interior control panel with gauge and you've got an OEM-like system.

That's how Firestone believes the OEM's eventually will see it, too.