The jaws on the model I have will open up to about 3", and I've pulled trees over 2" with it, but it can be a struggle if the tree has lots of side roots. I think it's pretty dependent on your soil and what type of tree you're pulling. Our soil here is a loamy clay, and I can only pull the bigger stuff during the wet spring season. Once the ground dries up in summer, it locks those roots in solid. You can get a lot of leverage with this tool, but if the ground is too hard, you'll just break off the tree at the stump. It helps sometimes to cut around the tree and slice through some of the upper roots with a spade. I use a "Root Slayer" shovel, which is another tool I wish I had discovered ten years earlier. It's an indispensable tool for any transplanting work.