What is the correct roller clearance for the dynamometer?

• A. The clearance must be 0 to 1 inch.
• B. The clearance must be 1 to 3 inches.
• C. The clearance must be 4 to 6 inches.
• D. The clearance must be 2 to 3 centimeters.

Answer: (B)

On a rolling dynamometer, you want the tire to sit firmly on the roller with a small, safe gap to prevent rubbing while still ensuring stable contact for accurate readings. The 1 to 3 inch range is ideal because it accommodates different tire sizes and sidewall flex, keeps the wheel centered on the roller, and avoids interference with guards or the dyno frame. A gap of zero to one inch risks rubbing or snagging, which can damage the tire or equipment and distort results. A gap of four to six inches would let the tire sit too far from the roller, causing poor contact and instability. A metric 2 to 3 centimeters is usually too tight for many setups and may not accommodate all tire sizes. So, 1 to 3 inches is the safe, practical standard.