Don't you think they'd sipe the tires at the factory if it was beneficial overall? Well, they do. Winter tires often come with sipes manufactured right into them, and on ice or certain types of snow, those sipes can be helpful.
But on summer tires, they're pretty useless -- unless you're driving on a racetrack in the rain. Last winter, a Minneapolis, Minn. The station claimed to have tested several siped passenger tires and declared that the process was worthless. It even implied that siping was a scam perpetrated by tire dealers to make a few extra bucks at the expense of gullible customers.
An upset Sprunk, who owns Phoenix, Ariz. He even contacted the person who donated the tires that were supposedly evaluated by the station but was told they had been discarded.
Sprunk discussed the situation with a Minneapolis lawyer, who agreed that he had a case. However, there was one problem: The most recent available test data on siping was nearly 20 years old! And that's exactly what he did with the help of Mobility Research, a Greenville, S. It wasn't cheap, according to Sprunk, but he says the results validated his claim that siping improves tire performance.
The P-metric tires were mounted on the drive axle of a test vehicle -- a modified pickup truck -- that was driven on stretches of medium-packed snow until the vehicle's test position right rear wheel broke traction. Ten runs were performed each day for three consecutive days. Siping provides even more of these gripping edges. Research has shown the most effective braking power occurs immediately prior to losing traction. Siping extends the window allowed for maximum braking power, by giving the existing tread a helping hand.
When that surface is more coarse or rough, your tires have even more work to do. Siping gives your tires micro-flexibility, resulting in a smoother ride. Tire noise, for one thing. Carpino said the tire will also wear irregularly, further increasing noise and possibly decreasing tire life, not increasing it as the tire shop claimed. All of these negative effects are only made worse on dry pavement, where an aftermarket siped tire will have greater braking distance, less traction, and will wear out more quickly.
All of which made siping seem to me like a scam, or at the very least a highly dubious buying decision. At around the two-minute mark in a video is this claim:. An independent study by the U. National Safety Council found that siping dramatically improves stopping distances, breakaway traction, and rolling traction on vehicles of all kinds.
The National Safety Council is an industry group, and when I contacted them to ask about the study referred to in the video, I got an almost instant response. The response was a letter NSC sent 18 years ago to a firm that makes siping machines and had been advertising its services as having a firm basis in NSC studies. The letter was a swift takedown that the NSC said still applies today:.
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