Question Tires of mismatched sizes: Answers Can be used only on a front axle. Can be used only on a trailer's axles. Should be corrected before driving. Improve fuel economy. Explanation Tires on the same vehicle should all be equally sized. Ensure your tires are not mismatched when inspecting your vehicle. This questions appears in the following tests: Massachusetts Passenger Nebraska Tank North Dakota Class B Knowledge Test Utah Tank West Virginia Class A Knowledge Test