That question is sort of like asking how high is up. So many variables, tire size, weight balance front to fear, tread aggresiveness, limited slip diff VS. open diff., ground conditions, and etc.
Only way I know of to do a true test is a drawbar test, that is to tie each vehicle with similar options to a hydraulic load cell on a two controlled level surfaces, ( first hard pavement, then soft graound). Compare empty drawbar pull with empty vehicle, then do same test with vehicles loaded to rated capacity. Then you have to determine if limit is pulling power or traction (Wheel slip). A rubber tired dozer can out pull a crawler on a hard surface but will loose out in soft ground, a log skidder will out pull a larger loader in soft ground because of the type of tires used and the final gear ratio.
