If you observe tires with a noticeable diameter difference of more than 3/8 inch on a dual axle, the recommended action is to:

• A. Ignore until maintenance
• B. Re-tire or replace to bring within tolerance
• C. Swap front and rear tires to balance
• D. Inflate the smaller tire to match height

Answer: (B)

When two tires share an axle, they must have essentially identical rolling diameters. If the diameter difference is more than a small tolerance (like 3/8 inch), the tires don’t rotate the same distance per revolution. That mismatch forces the axle and wheels to compensate, which can cause vibration, uneven wear, excess heat, and added stress on bearings, brakes, and the tire sidewalls. The safest and most reliable fix is to bring the pair into spec by re-tiring or replacing so both tires have matching rolling diameters within tolerance. This restores even load distribution, smoother operation, and reduces the risk of tire failure.

Swapping tires around won’t fix the underlying difference in circumference, and inflating the smaller tire to “match” height doesn’t change its actual diameter and can create unsafe pressure and load conditions. Ignoring the issue is unsafe and can lead to more serious problems down the line.