A vehicle is brought into the shop with a poor fuel economy concern. Technician A says that installing larger wheels and tires can throw the odometer off and cause this concern. Technician B says that installing a higher-ratio final drive gearset can cause this concern. Who is correct?

The correct interpretation here focuses on the statement made by Technician A regarding larger wheels and tires. Installing larger wheels and tires can indeed affect the vehicle's fuel economy and odometer readings. When larger wheels and tires are used, the circumference increases, resulting in the vehicle traveling a greater distance than what the odometer records. This discrepancy can lead to the perception of poorer fuel economy since the fuel consumption appears higher compared to the distance actually covered. As a result, the calculated fuel economy (miles per gallon) could be negatively impacted due to the increased distance indicated by the larger tires.

While Technician B's comment about higher-ratio final drive gearsets has some merit, it is less directly related to the fuel economy concern in the context given. A higher ratio typically means a more efficient use of the engine's power at cruising speeds, which might improve fuel economy rather than degrade it. Therefore, the more direct link to the poor fuel economy concern is found in Technician A's assertion regarding larger wheels and tires.