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Aspect Ratio

Aspect Ratio, in tire terminology, applies to the ratio of the height of the sidewall tire divided by its overall width. A lower aspect ratio implies a shorter, wider tire.

  • In tire terminology, the ratio between the height of a tire from the wheel rim to tread, and its width, from sidewall to sidewall, is known as the aspect ratio or tire's profile. The first tires were circular tubes with 100 percent aspect ratios.
  • It was later discovered that a tire handled better when it was mounted on a wider rim, making tires wider without increasing their height. These low-profile tires put more tread on the road and gave better handling, better load-carrying capacity, and longer life than the old symmetrical tires.

Axle Ratio

The ring gear has many more teeth than the pinion gear. This produces a gear reduction through the differential. Depending on the vehicle and engine design, passenger car axle ratios vary from 2:1 to about 4:1. The ring gear has from two to four t times as many teeth as the pinion gear. Therefore, the pinion gear must rotate from two to four times to turn the ring gear once.

  • The actual gear ratio through a drive axle is the axle ratio or final drive gear ratio. It can be calculated by diving the number of teeth on the ring gear by the number of teeth on the pinion gear.