The tires on one side of a drive axle are 2 inches taller than the tires on the other side. This condition could cause which problem?

• A. Too much ring gear wear
• B. Too much lubricant loss
• C. Too much rear pinion bearing wear
• D. Too much differential pinion (spider) and side gear wear

Answer: (D)

Understanding how a differential works helps here: the differential lets the two wheels on an axle rotate at different speeds, using the spider gears connected to the side gears to balance torque between the wheels. If one side has a taller tire, that wheel travels farther per rotation. So even going straight, the wheels aren’t rotating at the same rate, and the differential must continuously accommodate this mismatch. That constant, uneven loading stresses the internal gears—the spider gears and the side gears—more than normal, leading to accelerated wear. The other components aren’t driven as directly by this mismatch, so they’re less affected in this scenario.