I recommend changing your tires the first chance you get. I have the Cooper Discover AT3 on my TH. These are excellent all terrain tires and are only slightly noisier than highway tires. Better yet you can get them in your tire size so you don't have to make any modifications to your TH to get them to fit. They have been great in snow, mud, sand and offroading all over the west from Oregon to Utah and everywhere in between. They are expensive but with this tire you get what you pay for.
