How To Read A Tyre

how to read a tyre

Tyre Designations

300-4 Tyre width 300 / Rim Diameter 4"
10x3 Former designation in inches:
Tyre Width 3” / Tyre diameter 10” ( =3” x 2 + 4”)
260x85 Designation in millimetres:
Tyre diameter 260mm / Tyre width 85mm
The former designation in inches converted to mm:
10” x 25.4 = approx. 260mm
3” x 25.4 = approx. 85mm
85/100-4 This is how the designation would be, had it been a passenger car tyre.
Tyre width 85mm / Profile 100% / Rim diameter 4”.
10x3.00-4 American designation, mainly used for low proflie and turf tyres:
Tyre Diameter 10” / Tyre Width 3” / Rim diameter 4”

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On the sidewall of a tyre you can find the load index and Speed Symbol following the key sidewall size markings.
  • The Load Index is a numerical code associated with the maximum load a tyre can carry
  • The Speed Symbol indicates the speed at which the tyre can carry a load corresponding to its load index.
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