SEATTLE-The battle over stud usage has driven at least one retreader nutty. Tire studs provide effective traction on icy roads; many claim their added traction saves lives. However, government officials in some areas allowing studded tires complain they are causing millions of dollars of road damage.
Instead of picking sides, Seattle-based Tech Tred has sidestepped the controversy by employing an age-old method of increasing snow and ice traction.
Since it began retreading in 1986, Tech Tred, incorporated as World Enterprises Northwest Inc., has used rubber mixed with tiny bits of walnut shells.
The crushed walnut shells help grip slippery road surfaces similar to kitty litter or sand placed beneath the tire, explained Tech Tred Manager Ed Fatkin. But, unlike metal tire studs, the shell bits can be used year-round without damaging road surfaces.
The shells act like thousands of gritty studs, gripping snow and ice. Then, as the tread wears down, bits of shell fall out, leaving tiny pockets that also help grip the road, according to Dick Johnson, president of Chehalis, Wash.-based DECA Rubber Inc., which supplies the rubber.
DECA buys the crushed walnut shell chips in 50-pound bags from a California company, then sprinkles them into the rubber as it is processed into strips for mold-cure retreading.
Putting such material into tread rubber is not a popular approach to increasing winter traction without causing road damage, but it's a plausible one, Mr. Fatkin said.
Tires mixed with walnut shells provide about 20 percent less traction on ice than those with metal studs. But they stop much better than studded tires on dry road surfaces, Mr. Johnson said.
Beside the traction tradeoff, walnut shell treads do have their downside. For one thing, they wear about twice as rapidly as those without shells, typically lasting through two or three snow seasons, Mr. Fatkin estimated.
And although such tires cost about half as much as studded new tires, they do run about $3 more than conventional retreads, Mr. Fatkin said, noting that the higher price is necessary to cover special production runs. The rubber itself costs 4 cents per pound more than the untreated variety.
Sales of walnut-shell retreads have increased from a typical 10 percent of Tech Tred's snow-tire business to about 16 percent this season, Mr. Fatkin said, largely due to local newspaper articles about the practice.
Sales of the walnut shell retreads are not enough to boost Tech Tred's margins, but the tires never have been sold for that purpose, Mr. Fatkin said.
``We feel it's a plus for our business because we are doing more for the public,'' he said. ``It gives the customer an extra option.''
Such retreads are produced only at a customer's request, he said. None of the tires are sent wholesale to the dealerships that the five-employee shop typically supplies with its other retreads.
Government- and tax-exempt vehicles, prohibited from using studded tires, make up the bulk of Tech Tred's walnut tire market, Mr. Fatkin said.