Equal will not clog your tire valves and is very suitable for offroad vehicle use. The Equal granules will never reach the valve core because of the fitment of the AirX Filtered Valve Core that comes with every bag of Equal. The AirX Filtered Valve Core is part of every proper Equal installation, no matter who tells you otherwise. If you purchased the Equal granules but were not provided AirX Filtered Valve Cores, you were not dealing with an authorized or trustworthy Equal stockist.
However, installing Equal in your tires will increase the time it takes you air down. The Equal granules will attach to the screen mesh in the AirX Filtered Valve Cores and will restrict the flow of air through your valve stems. Unless you first push air through the valves before airing down in order to push away the Equal granules from the protective screen, you will find your airdown time will increase due to the restricted airflow. This restricted flow is easy to eliminate by injecting some air into the tires to clean the screen mesh on the AirX Filtered Valve Cores prior to airing down. If you do not flush your tires' valves prior to airing down, then air will merely trickle out of the valve stems because of the restricted airflow.