Steering ratio refers to the ratio between the turn of the steering wheel (in degrees) or handlebars and the turn of the wheels (in degrees).
[1] The steering ratio is the ratio of the number of degrees of turn of the steering wheel to the number of degrees the wheel(s) turn as a result.
For example, if one and a half turns of the steering wheel, 540 degrees, causes the inner & outer wheel to turn 35 and 30 degrees respectively, due to Ackermann steering geometry, the ratio is then 540:((35+30)/2) = 16.6:1.
In normal and lighter cars, the wheels are easier to turn, so the steering ratio doesn't have to be as high.
[2] On the other hand, the steering effort needed will greatly increase.