While highway tires and all terrain tires have them built in, most mud tires do not have sipes in their tread blocks. This not only increases wear and heat in those tires, but can also decrease traction. We’ll briefly show you how to sipe the tread blocks and explain how and why it works.
There are two things you can do to your mud tires to increase traction; grooving and siping tires. We’ll talk about grooving in another article, but know that they are not the same thing. Grooving involves removing full chunks of rubber from your tread blocks.
Siping, on the other hand, is a process to cut a small relief in the tread block ninety-degrees at horizontal of the tire. You’ll barely notice that you’ve made the cut if you’ve done it right as you’re only just cutting a relief and not taking any more rubber out of the tread block.
So, how does cutting a little relief actually help your mud tire gain traction if you’re not cutting a groove out of it? Simple, siping the tread block makes it more pliable.
If you were to view the tire under a microscope as you travel down the highway you’d see that the road is not perfect and is actually very jagged.
A single piece of mud tire lug can’t deform to actually gain grip on that surface and will actually squirm more than it grips. Cutting sipes will allow the blocks to move in that micro-surface and form to the road that much more for better handling, traction, and even ride comfort.
To sipe your tires, you’ll first need to grab a hot knife, safety glasses, and gloves that can protect you from heat. Make sure the one you use has enough of a handle that will make your cuts steady and gets hot enough to melt the rubber the knife blade hits, usually about 250 Watts is enough.
You can use a regular utility knife but why make life harder? You’ll then cut the tread blocks at ninety-degrees horizontal of the tire tread, going across the block.
You can cut multiple sipes into the block, but don’t make it into a sipe that happens to have a tread block. Do up to six on bigger lugs and two on the smallest ones.
Finally, when you make the sipe, don’t go all the way through the tread block. Cut down to about 3-4/32-inch from the bottom of the lug, or 1/2-inch deep at most.
Also, on the outer lugs that are near the sidewalls, you shouldn’t really sipe them, but if you do, don’t make a cut all the way across.
There is a risk of some chunking on those lugs since they do flex the most from turns and movement in the sidewall over the road.
That’s it, now you just have to do it the entire 31 to 42-inch circumference. Good luck and be safe while cutting!