Axle Ratio
On rear-wheel-drive vehicles, rear-axle ratio is an important part of a successful towing equation. It is expressed as a ratio between the driveshaft revolutions per minute and the rear axle’s revolutions per minute (see illustration). It is always given as a numerical expression like 4.1:1. This means the small pinion gear at the end of the drive shaft must rotate 4.1 times for every single rotation of the rear axle.