WTR stands for "Walk-to-Ride," a rockered sole standard that gives you better traction and comfort when walking compared to traditional flat alpine soles. The curved profile and rubber tread make a real difference when you're hiking to a backcountry line or just crossing an icy parking lot. You'll typically find WTR soles on freeride and some touring-oriented boots.
The catch is binding compatibility—WTR is not the same as GripWalk, and it's not universally compatible with all alpine bindings. Some binding models from certain brands accept WTR soles, while others don't. It depends entirely on the specific binding you have.
Before buying WTR boots, check your binding's manual or look for a WTR-compatible marking on the binding itself. When in doubt, have a shop tech verify the pairing. Using an incompatible sole in your bindings can cause unexpected releases or failure to release when you need it to—so this is not a detail to guess on.