Final answer:
A red triangle Slow Moving Vehicle sign should be placed on any vehicle that travels at less than 25 km/h to ensure road safety and alert faster-moving vehicles.
Step-by-step explanation:
The question pertains to a standard safety sign used on vehicles that travel at certain slow speeds to warn other road users. In many regions, a red triangle Slow Moving Vehicle sign should be placed on any vehicle that travels at less than 25 km/h. These signs are typically found on the back of farm equipment, construction machinery, and other vehicles that are not designed to reach higher speeds on public roads. It's crucial for road safety that vehicles capable of only low speeds warn other traffic participants of their presence to prevent accidents due to the difference in speeds.