This comes with a #4 Head and Blades. It's between 3/16"-1/4" wide when cuts are made into rubber. I grooved the outer lugs on my Nitto Trail Grapplers. Factory grooves were worn down almost completely. This opened them back up to a little wider the factory. Worked great. Make sure you let the unit heat up for the recommended time before you start to cut, and go slow when cutting. It's not a race car-paced groover.

I bought this to add grooves to mostly worn mountain bike tires to get more usable life out of them. Grooving is very easy but this particular one I bought only comes with #4 head and blade which is probably a good size for a car or atv tire, but way to big for the knobs on an aggressive mtb tire. I bought the smallest blade and head, #1, and this is the result of my first try.

Read the instructions. I set mine to cut a little deeper than I wanted at first, so my advice is to be conservative with depth (start shallow) and go deeper if needed. If you let this baby heat the recommended 15 minutes it works very well. Be warned that it gets hot as hell, you do not want to touch it or lean it against anything. If you run Shinko 804/805 on your Moto you know how fast they turn into one solid knob across the tire. This tool transforms the rear tire back to new, in under 15 minutes.

Was skeptical at first but works great! I was going to buy a set of tires for my razor due to the tread pattern not being aggressive enough but decided to try this. Glad I did! Seems to be very well built like an old tool you'd find in your grandfather's toolbox. Stays hot even after constant use. Once you learn a couple of tricks it's pretty fast. The first tire took me 40 mins the second tire was under 30 min.

The tool cut cold tires with outside temperatures in the 30s like butter, I was able to reopen the shoulder of my drive tires, flip the blade around, and add siping to the tread blocks, this all made a huge difference in the performance of the tires in the snow and mud.