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Tyre size Gear ratio Calculator
Your Tyre Size
Your Car TyreUpsize Tyre
Tyre Diameter024
Static Radius0-0
Dynamic Radius012
Rev / Kms013437
OE gear ratio : 1
Size change Gear ratio0 : 1

Gear ratio defines vehicles torque and power delivery behavior. When tyre is upsized / size changed the effective radius changes which results change in effective gear ratio.

Original size tyre of 205/55R16 if replaced with 215/50R16, this result in higher tyre dia which results in higher torque delivery. Effectively lower gear ratio. If Original gear ratio is 3.55 , with 215/50R17 this will change to 3.47.

Tyre DiameterThis is the Geometrical diameter of an inflated tyre at the outermost surface of the tread, or twice the inflated section height of tyre plus nominal wheel rim radius. Tyre diameter is dependent on Tyre width, aspect ratio and wheel rim diameter. In service condition tyre diameter increases marginally due to carcass relaxation. The tyre diameter acts just like another gear in your vehicle and matters a lot in defining the economy and vehicle acceleration.
Static RadiusStatic rolling radius or "Static radius" is the distance between wheel center and the point on the circumference of a tyre taking compression into account. It defines vehicle stance and ground clearance in static condition. Due to tyre compression at corresponding load ,tyre static radius reduces from normal geometrical radius.
Dynamic RadiusDynamic rolling radius is the actual radius of tyre when the vehicle is moving. This takes into account the centrifugal force that acts upon the tyre during revolutions.
CircumferenceThe linear distance traveled by a tyre in one revolution. It is derived from from Dynamic rolling radius as it represents the true radius of tyre during motion. It is useful to compute tyre speedometer and odo meter calibration errors.
Rev / KmsMeasured number of revolutions for a tyre traveling one kilometer. This can vary with load and inflation pressures.
Gear ratioGear ratio is critical parameter for defining vehicle character, tyre change also indicate change in torque delivered when we back calculate this effects change in gear ratio. This calculator symbolizes the effect of change in tyre to effect vehicle power and torque delivery..