Final answer:
PennDOT mandates that vehicles must have an annual safety and smoke emission inspection, which can be done up to 90 days in advance of the due date.
Step-by-step explanation:
PennDOT (Pennsylvania Department of Transportation) requires vehicles to undergo a safety and smoke emission inspection every 12 months. In addition, your vehicle may be inspected up to 90 days before the due date of the necessary inspection.
This stipulation ensures that vehicles on the road meet safety and environmental standards set by the state. It's important to adhere to these regulations to avoid potential fines and legal issues.