A disc brake rotor's total indicated runout reading should be

• A. 0.001 to 0.002 inches
• B. 0.003 to 0.005 inches
• C. 0.006 to 0.008 inches
• D. 0.01 inches or less

Answer: (B)

Total indicated runout shows how much the rotor deviates from a perfectly true circle as it spins. Keeping this variation within a tight but achievable range ensures brakes contact the rotor evenly, avoiding pedal pulsation and uneven pad wear. The commonly specified tolerance is about three to five thousandths of an inch. That range balances the reality of how rotors and mounting surfaces vary with manufacturing and service, while still being tight enough to maintain smooth braking. If the reading exceeds this tolerance, the rotor may need resurfacing or replacement, and you’d also want to check for issues like hub surface condition or caliper mounting alignment that could contribute to excess runout. Extremely small readings aren’t necessary to chase beyond what the system requires, and readings well above the limit would be obviously problematic for braking performance.