Why Sipe Your Tires?

The tire mounts inside the siping machine and rotates slowly as the tire receives its cuts from side to side.

The cutting blades come in different diameters from 5/23-inch to 13/32-inch and larger. The spiral-wound head above the cutting wheel actually determines the depth of the siping.

When installed on the head, the blade is twisted to leave a gap to form the separate rows of siping.

This is how the cutting head is placed on the tire surface when it's ready to cut. Notice the water tube at the right, spraying water to lubricate and cool the cutting head.

The knife is opening the new 1/4-inch-deep siping cuts about 1/2 inch apart around the tire diameter. Notice the larger factory siping cut coming into the photo at an angle.

Siping on this used tire that still has good tread left can be done ideally just before winter. The factory L-shaped siping can still be seen on the top of the lugs. When the siping is pulled open during traction and braking, the microedges start grabbing the road surface.

A lot of steam comes up from the tire during the process of moving the head across the tire. Circling the tire takes about 10 minutes and costs anywhere from $12 to $20 per tire. Depending on road conditions, the siping (slices) will open up slightly after 500 miles to a couple thousand miles and be visible (as shown here).

The big blocks or lugs on this 4WD tire give a lot of off-road traction, but that can be improved by siping the lug surfaces.

This tire on Brad Haga's hunting truck shows the little pebbles and a few sticks that have actually stuck between the siping cuts. From his experience with siping tires and driving on them, he says these sticks and pebbles don't present any problems and will probably come out as soon as he is back on the highway.

Even the factory did as the aftermarket suggests by siping just the center of the tire. This is a tire that has both center siping and studs added to the outer edges for real winter conditions. Aluminum studs with steel centers are implanted into the edges of the tire using a pneumatic gun. Some states have different regulations determining the stud material, since they deteriorate the highway surface.