Tire siping is like taking a razor blade to cut the tread of the tire. For smaller tires you put the siping close together, the largest the tire the further apart the sipes should be. In the tire shop, we had two knife forms, one for passenger tires and one for commercial tires.
Saying you got a tire siper I'm inclined to think you have a groover. a groover cuts a valley in the tread of the tire. A groove will remove material where siping does not remove any material.
The tool I have holds multiple razor blades at the same time and heats up to make it easier to cut. They're just straight blades, not loops. It's adjustable so I can change the spacing and the depth of the blades. I'm not quite sure what to set it to. The last time I sipped the tires I did it with a single blade and I didn't make that many cuts since it was kind of a pain in the ass.
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This was how I siped them last time. I'm not sure what the depth was since I was just kind of winging it before. I'm wondering if I should have more sipes on each lug compared to this.