Armed with new independent tests that show improved traction on prepared snow, Saf-Tee Siping & Grooving Inc. is setting out to bring more tire dealers into the siping fold.
Wes Sprunk, owner of the Phoenix-based company, said he sought the independent testing after a television station in Minneapolis aired what he described as a negative news story last fall about siped tires.
``I wanted to get something the tire dealer would recognize as being official,'' Mr. Sprunk said.
Saf-Tee Siping makes the siping equipment, which range in price from $5,525 to $11,275, according to the company's Web site. The machines cut small slits at 90-degree angles across a tire's tread. Distance between the sipes and the depth of the sipes can vary. The slits are designed to create gripping edges that provide extra traction, better braking and heat dissipation, the company claimed.
While some dealers swear by siping, others still aren't convinced.
``We do a ton of it in this part of the country,'' said Andy Sherry, manager of the Les Schwab Tire outlet in Missoula, Mont.
But John Quirk, president of VIP Discount Auto Centers in Lewiston, Maine, said advancements in tire technology mean dealers can find products off the shelf that answer a customer's traction needs without the extra cost of siping.
Mr. Sprunk acknowledged siping seems to be more popular in the West than along the East Coast.
``It definitely is more of an item we sell in the Snow Belt,'' he said.
Montana is a good example of a lush siping market because the area basically has two seasons: summer and winter, Mr. Sherry said. As a result, many customers prefer tires that can handle almost any conditions.
In the tests, conducted by Mobility Research Inc. of Piedmont, S.C., pickup trucks were run on a prepared snow surface at 5 mph. Computers tracked the percentage of slip for the tires tested, including two siped and two non-siped Michelin Pilot Sport tires, size P205/50ZR16, and one siped and one non-siped Goodyear Eagle LS tire, size P205/55R16.
According to the results, the siped versions of both the Michelin and Goodyear tires showed improved traction over their non-siped counterparts. The Michelin tires gained 62.5 percentage points in their average rating. The Goodyear tires improved by 32 percentage points. The percentage ratings were based on a national industry standard procedure used as a baseline for tire tests, said Mobility Research President Paul Schultz.
While this test was controlled to only measure the actual performance of the tire, few motorists drive 5 mph on a constant surface of snow. But Mr. Schultz said the difference is large enough that similar results are possible on other snowy surfaces.
As Mr. Sprunk aims to sell dealers on siping with these findings, he said dealers themselves have to sell siping to their customers. He said his company trains dealers who buy the equipment how to use the machines, but salespeople must be vigilant in suggesting the service to motorists.
Mr. Sherry said his shop sipes up to 60 percent of the tires it sells. For light truck tires, that number jumps to 70 percent. He said siping's popularity may be helped by more states outlawing-or at least charging high fees-for studded tires. The service also is advertised on Les Schwab Tire Centers Inc.'s company Web site.
But Mr. Quirk said his customers almost never ask for the service, and he doesn't believe a market exists to offset the investment. As such, he doesn't see siping on the horizon for VIP's 49 locations in New England.
Secondary concerns also include possible impacts on a manufacturer's warranty and potential liability issues. ``Anytime you touch a tire, you have to have that in mind,'' Mr. Quirk said of lawsuit potential.
Mr. Sprunk said tire makers won't officially condone siping, but it doesn't affect their warranties.
But according to a fact sheet for tire owners, Goodyear said its warranties do not cover any tire that ``has been intentionally altered to change its appearance,'' including white inlay on a black tire, regrooving or siping.
Dan Zielinski, vice president of communications for the Rubber Manufacturers Association, suggested dealers contact a manufacturer before making any changes to a tire. He said the RMA has no official position on tire siping.
He said calling a tire maker can give the dealer and customer peace of mind, ``so they can assure their customer for sure there's not potential implications with the warranty by physically changing the tire,'' he said.