It is unlawful to operate a motor vehicle on a highway that has what feature on its wheels?

Operating a motor vehicle on a highway with flanges or lugs on its wheels is unlawful because such features can significantly compromise the safety and functionality of the vehicle. Flanges or lugs are typically used for specialized applications, such as on certain types of construction equipment or in off-road scenarios, but they are not suitable for standard road use. These features can cause instability, increase tire wear, affect handling and stopping distances, and pose a danger to both the driver and other road users.

On the other hand, options regarding loose tires, excessive air pressure, and spare tires address concerns that may arise but do not inherently make the vehicle unlawful to operate on a highway. Loose tires can present a hazard but may not always lead to immediate legal repercussions without evidence of impairment. Excessive air pressure could potentially lead to tire blowouts, but again it is not specified as an outright prohibition. Spare tires, while not ideal for long-term use, are often legally permissible as long as they are in safe operating condition. Thus, the presence of flanges or lugs is distinctly classified as unsuitable for highway travel, which makes that option the correct choice.