To Sipe Or Not To Sipe

To Sipe Or Not To Sipe
SEATTLE - Buy a new set of tires and there's a good chance you'll be asked if you'd like those new treads siped. The siping process involves cutting small slits into the tread to create thousands of extra edges. This is supposed to improve traction on wet and icy roads, deliver a smoother ride and extend tire life by reducing heat build-up.

A number of tire stores, including Les Schwab ( and Discount Tire (, actively promote siping. On its Web site, Discount Tire says independent test confirm that its siping procedure can improve traction "up to 200%!"

"It's at the point now that customers ask for it when they come in, " says Chris Stone, the manager of the Bellevue Discount Tire store.

Stone is a big believer in siping. "The benefits are huge," he told me, "not only from the standpoint of stopping. "It gives a better ride," he says, and extends tire life "because it dissipates heat; all those little biting edges open up and cool the tire quicker."

In the last few weeks, a number of KOMO News listeners and viewers have written me to ask if they should have their new ties siped. They wanted to know if it's worth the extra $10 a tire.

There isn't a lot of independent information available about tire siping. Most of what's on the Web is either advertising claims or testimonials from car buffs. So, I made a bunch of calls and spoke to a number of people in the field about this.

The automotive experts at Consumer Reports told me they advise motorists to steer clear of siping. The magazine's Eugene Petersen told me "there's no question siping gives a tire more edges to grip the road," but he cautioned, "it can alter the tread pattern so the tire wears more quickly."

Consumer Reports gives another reason for recommending against siping - they say tire makers are "concerned about this practice" because it changes the tire's original design.

Dan Zalinsky with the Rubber Manufacturers Association verified that tire makers "have some difficulties with post-manufacturing enhancements that cut into the tire." If a consumer has a concern about grip, he said, they should look a tire that matches their needs, rather than trying to alter the treads on the tire they selected.

I also spoke Andy Pomeroy, Regional Automotive Manager for AAA Washington ( who pointed out that today's passenger tires are significantly better than the tires that siping was designed to help. "Tire manufacturers have engineered their tires to find the best balance of tire wear, traction and noise in a particular tread pattern or rubber compound," he says.

Pomeroy, who is also an ASE Master Technician, spoke to a number of major tire makers, and was told that "adding siping to a tire will change the way the tread wears."

Whether you believe in siping or you're a skeptic, one thing everyone agrees on - some tires cannot be siped; that would include high-end performance tires or tires that have been siped at the factory. Some snow tires now come pre-siped

Keep in mind, siping a tire could void the manufacturer's warranty, so if you decided to have your tires siped, you need to make sure the tire store will stand behind their work if there's a problem.

For more information:

Read Herb's tip on top-rated all-season and winter tires.