Indiana Code Title 9. Motor Vehicles § 9-19-3-8

(1) Actual road tests conducted on a substantially level (not to exceed a plus or minus one per cent (1%) grade), dry, smooth, hard-surfaced road that is free from loose material, and with stopping distance measured from the actual instant braking controls are moved and from an initial speed of twenty (20) miles per hour.

(2) Suitable mechanical tests in a testing lane that recreates the same conditions.

(3) A combination of the methods described in subdivisions (1) through (2).