Before aligning the front wheels on a truck, which of these should be checked?

Before aligning the front wheels on a truck, checking the tire balance is crucial as it ensures that the weight of the tire and wheel assembly is evenly distributed. An unbalanced tire can cause uneven wear, steering vibrations, and potentially lead to inaccurate alignment readings. When the tires are balanced properly, it contributes to a more stable and accurate alignment process.

While aspects like tire pressure, trim height, and wheel bearing adjustment are also important in the overall maintenance and performance of a vehicle, they do not directly influence the initial setup for wheel alignment to the same extent as tire balance. Tire pressure should indeed be checked to ensure optimal handling and wear characteristics, and trim height is important for measuring suspension geometry, but if the tires are not balanced, it can lead to misleading alignment results. Proper wheel bearing adjustment is crucial for safe vehicle operation but does not directly impact the alignment procedure. Therefore, ensuring tire balance is a key step before performing an alignment on the front wheels.