Proving ground purgatory for tires

Aug. 23, 2006
SAN ANGELO, TX. The sparse shade of a mesquite offers Charles Ruff little protection from the Texas sun

SAN ANGELO, TX. The sparse shade of a mesquite offers Charles Ruff little protection from the Texas sun. It’s not hot here on the edge of Goodyear Tire & Rubber’s proving grounds—it’s scorching; a blistering 115º F out on the 58 miles of roads and 53 test surfaces that dot this 7,200 sq.-acre location.

“Even though that part of the track is supposed to be ‘steering neutral,’ you need to keep your hands on the wheel all the same or you’ll lose control of the truck,” Ruff said, pointing to banked curves on Goodyear’s 8.2-mi. highway test track for tractor-trailers. He takes a quick pull from an ever-present bottle of water. You drink water every half-hour out here, whether you’re thirsty or not.

Two International 9400 tractor-trailers are making fast laps on the highway course, punching 65 mph with the A/C and headlights on, conducting yet another fuel economy test. This one demonstrates the fuel saving potential of the company’s new Fuel Max tire line. Fuel economy is now such a huge concern that the proving grounds staff is doing more of these tests than ever before, explained Mike Hood, development engineer.

See Goodyear rolls out Fuel Max tires

“We’ve done more fuel tests this year than the last eight years combined,” he said. “In the past, we’d run one maybe one a year. This year we’re conducting them once a month, and that might increase to two a month in some cases before the year is out.”

The blistering heat, however, is proving to be a double-edged sword of sorts for those tests, Hood added. Heat is a tire’s worst enemy, which explains why the proving grounds are here in San Angelo, a place that gets only 20 inches of rain a year. But when diesel fuel gets hot, it expands--and thus skews the fuel economy data Goodyear’s engineers are trying to collect.

“When the fuel’s temperature jumps from 80º F to 125º F, it doubles the test’s inaccuracy,” Hood said. “So we added fuel coolers to our test trucks to eliminate that problem.”

“Data integrity is critical to the whole tire testing process,” added Ruff, a former truck driver turned engineering technician, responsible for making sure the data recording devices for Goodyear’s tire tests are all calibrated correctly. “Bad data on the testing end affects how tire compounds are made, tread patterns are designed, etc. You need to have good, accurate testing data to develop the best tires possible.”

Lithe and weathered, Ruff looks more like a cowboy than an engineer. He joined Goodyear after a 13-year trucking career that included hauling cattle and working for then LTL carrier Yellow Freight.

“The point of all of this is to beat tires up to see how they perform under all kinds of unusual stress,” he explained. “Because if a tire can survive here, it can survive anywhere.”

Randy Brayer, manager of the proving grounds, said tire testing used to take place on the town’s public roads until 1957, when Goodyear built its first test surface: a circular five-mile high-banked loop that’s now retired as laboratory testing replaced it.

In 1994, Goodyear built a special vehicle dynamics area (VDA) complete with a grand-prix style road circuit for dry surface performance testing, and a Wal-Mart sized parking lot equipped with water pipes to create wet road conditions, followed in 1998 by a (thankfully) air conditioned safety tower to allow engineers to view the entire area.

“A lot of car companies such as Ford, DaimlerChrysler, and others use the VDA to test our tires,” said Brayer. Most of the time, however, his 23 engineers and other 70 staffers are doing all the work.

Gravel and dirt roads, off-road tracks, even a “tractor pad” to test agricultural tires all add to the capabilities of the proving grounds to test a wide variety of tires under a variety of conditions. For trucks, that includes a long “blow out” lane and “regulation pothole” to see if tires can withstand excessive skidding and poking without losing chunks of rubber.

A lot of technology comes into play in other locations to test tires with minimal manpower. One of the resident geniuses at the grounds, Glen Luther, senior development engineer, provides one of many examples. Gauging tire traction on slick roads is done using a camera system installed under a 4-in. thick glass plate buried in one of the roads under a metal canopy. Vehicles drive over the plate, wetted down with a thin later of water dyed green for better contrast, with the tire photographed from underneath to determine traction. The goal is 90% or more traction, Luther stressed.

Luther developed a robotic arm that automatically cleans and resets the water level on the plate after every vehicle pass. He also developed a wireless communication network to transmit the data from the cameras to the vehicle’s driver, who, using a computer in the cab, can then analyze the tire’s “footprint” and send that data back to the main laboratory. This way, one engineer can conduct a whole series of tests that would have required three or more people in the past.

Yet hard physical abuse is still the name of the game. Interlocked concrete chevrons form a long broken road that trucks are driven over 120 times or more to see how tires hold up. Trucks back up against and alongside steel reinforced curbs to gauge sidewall hardiness. There’s even a special hydraulic jack a truck backs up into that then twists tires a full 45 degrees or more to see how the tread cap fares.

“It’s brutal, but it’s worth it,” said Ruff. “Tires, especially truck tires, get worked hard out on the road. We make sure that they can survive that by pushing them even harder out here.”

To comment on this article, write to Sean Kilcarr at [email protected]

About the Author

Sean Kilcarr | Editor in Chief

Sean previously reported and commented on trends affecting the many different strata of the trucking industry. Also be sure to visit Sean's blog Trucks at Work where he offers analysis on a variety of different topics inside the trucking industry.

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