I had a hell of a time finding winter tires I liked, but finally bought some US made Toyo M-55s. I had to drive down from Montreal to the US to pick them up, but it was well worth it since the US made M-55s are pinned for studs. These tires are used extensively by commercial fleets and working pickup trucks out west and up north. They easily last 80k or more and many owners sipe them. There are siping machines that exist, but there none in Montreal, so I had to hand-sipe mine. Hand-siping also does a better job, supposedly, because you can stay away from the edges of the lugs. Automated siping machines are just a big cork-screw cutter that cuts 1/2" wide sipes along the tread circumference.

The first step in hand-siping is getting yourself a 250 watt 'heated knife' off eBay or elsewhere. It has to be very hot before using, so clamp it in a vise and wait a good 15+ mins. The top section should start glowing red - then it's ready to use. :-) I had to use some flash here, so the red glow doesn't show up very well.

The Toyo M-55s can be siped deeply if you're not pulling a heavy trailer, so I set the depth of the blades to a little less than 3/8" (12/32"). People that haul trailers may opt for 1/4" instead and sipe the tires again once the first sipes are nearly worn off.

It'll take a good 30-45 mins to sipe each tire. It also takes some effort to push the heated knife through the rubber. My plan is to take it easy and sipe one tire per day. :-) The heated knife kit should come with a dozen blades or so, and you may need to change the blade each time you use the knife. They bend back a bit (so you loose a bit of depth) and seem to become brittle after they cool down.

I opted for 6 cuts (3 passes of the knife) per center lug. I think this is fairly reasonable for a winter-only tire. If I was running this tire as an all-season, I would probably go with 4 cuts (two passes) instead. Although sipes are excellent for traction on wet surfaces and ice, they can chunk when rock crawling off-road and/or driving long distances on gravel roads. For this same reason, you should not sipe the edge lugs. As I mentioned earlier, you don't want to cut too deep if you're pulling a trailer. The Toyo M-55s are well known for their ability to take deep sipes without chunking, but other tires may not be as resistant. I used a silver marker here to show the pattern I used.

The picture on the left is what it looks like after the tire has been siped. Excuse the dog hair - hot rubber seems to be very good at picking it up off the carpet. :-)

There you go - pretty simple. The picture bellow shows where I start siping the lugs. I then do another pass on each side of the first cut, for a total of 6 sipes.

View the Jeep > Projects > Hand Siping Toyo M-55s folder...