(FORTUNE Magazine) – Al Cohn, marketing manager for commercial systems engineering at Goodyear Tire & Rubber, really knows his tires. A 16-year company veteran who started as a tire designer, Cohn, 38, helps about 500 salespeople and field engineers use performance data stored on Goodyear's mainframes. He also makes sales calls on big accounts like Navistar and Yellow Freight. He told Fortune how he uses information systems to help give the Akron giant a marketing edge.

What's it like being an engineer and a marketer? Tires are a big portion of the budget in any fleet, so customers like to talk to a technical person and see lots of data on price and performance before they buy. I travel on sales calls about half the time and spend the rest developing computer systems for salespeople to use.

How can a mainframe help land a sale? We've got six years' worth of performance data, such as statistics on tread wear, durability, and fuel economy, as well as information on pricing, tire sizes, and competitors' products. When you have that much information, you need a mainframe: No portable system can crunch the numbers and generate charts and graphs as fast. During a sales call we hook into the mainframe by phone and can answer specific questions from the customer -- for example, how a particular tire performs on Mack trucks that haul coal in Kentucky with an average load of 6,000 pounds per tire. In eight to ten seconds we can generate a graph with the answer and print it out. In the old days people would ask questions like these, and we'd say, ''Sure, let us look in our files, and we'll get back to you in two weeks.''

What hardware and software lets you do this? The equipment I carry depends on what we're trying out. Right now I have an IBM ThinkPad 720C, which is a notebook computer with a color screen. We chose the ThinkPad in part because of its removable hard-disk drive, which makes it possible to carry around several different drives loaded with presentation material. The ThinkPad's optional credit card-size modem lets me call the mainframe back in Akron. We use software called Attachmate EXTRA! for Windows to make the ThinkPad function like a mainframe terminal. Attachmate lets you switch from PC to mainframe programs with ease, and also send files back and forth. We've written our own code for producing charts and other graphics to display the information stored in the database. I print out charts using my portable printer, a Hewlett-Packard DeskJet Portable. To put everything in nice presentation form I use Microsoft Powerpoint for Windows or IBM Storyboard LIVE! Storyboard LIVE! also lets me add animation. Sometimes I bring an nVIEW MediaPro LCD display panel that fits on an overhead projector so I can show everything I'm doing on the notebook on a big screen. If the customer has a VCR and TV, I'll use that to show clips of a truck rolling down the highway. It's my own kind of multimedia show.

Could this setup help sell things besides tires? A system that lets salespeople tap into the mainframe would work for any industrial product that has extensive data associated with it, from chemicals to corporate jets. But you can't sell this way unless you're committed to constant testing of the latest equipment and constant training. When you develop your system, you can't be shortsighted or pinch pennies. The important thing is to make sure that the system is open-ended so you can add to it. For instance, this fall we hooked up a Hewlett-Packard ScanJet IIc to digitize photos of trucks for presentations. You should make sure you have a lot of support people, such as specialists in communications software; there's no way one person can be an expert in everything. And you should attend trade shows and seminars to keep abreast of where technology is heading. You can't talk to computer people unless you know their buzzwords.

BOX: WHAT HE USES

IBM THINKPAD 720C This 7.6-pound portable boasts a large color screen, a removable hard drive, and IBM's popular pointing device. Recently superseded by the 750C, at $4,699.

ATTACHMATE EXTRA! FOR WINDOWS Software that connects your PC to your mainframe, letting you exchange files and cut and paste data between mainframe and PC programs. Price: $425.