Final answer:
The federal regulations set an axle weight limit of 34,000 pounds on a tandem axle (four feet apart).
Step-by-step explanation:
The subject of this question is Social Studies, which encompasses the study of various aspects of society, including government, economics, and laws and regulations.
In this case, the question is related to federal regulations, which fall under the branch of law within the field of Social Studies. The topic specifically pertains to axle weight limits for tandem axles, which is a concept related to transportation and infrastructure.
The federal regulations set an axle weight limit of 34,000 pounds on a tandem axle that is four feet apart.