In general, a prime mover with a horsepower rating of between 300 and 500 will be sufficient for most towing applications. However, if the trailer is very heavy or the terrain is very difficult, a prime mover with a higher horsepower rating may be required.
It is important to note that the horsepower of a prime mover is not the only factor that determines its towing capacity. Other factors, such as the weight of the prime mover, the gear ratio, and the axle ratio, also play a role.