There are a few different ways you can use to prevent the tongue of your Timberland boots from sliding down. One way is to use a shoelace or a shoehorn to help keep it in place. Another way is to tuck the tongue underneath the laces so that it stays in place while you're wearing the boots. Finally, you can also try wearing a pair of socks over the tongue to help keep it in place. Whichever method you choose, make sure that you're comfortable with it before you head out for the day.