Crawl ratio

Crawl ratio is a term used in the automotive world to describe the lowest gear ratio a vehicle is capable of. The crawl ratio of a vehicle is affected by the entire drive train, including transmission, overdrive differential and tires, and can vary greatly between automobiles.

The lowest gear of most vehicles is either first gear or reverse, but when referring to crawl ratios, only first is normally taken into consideration. The crawl ratio is aptly named, for when a car is using its lowest possible gearing, it moves the slowest at a particular engine rpm. The usefulness of a high crawl ratio is to provide the driver with the greatest possible torque to pull large loads or climb steep inclines. Crawl ratios are most often used in the context of large SUVs or trucks and off-road vehicles.