Here you can convert Tire-Size designations from metric to imperial and the other way round.
Enter the Values that you want to convert into the matching line and click the "Calculate" button
at the end of this line. The converted Values will show up in the other lines.
Hint: This is a pure mathematical calculation and can result in for tire sizes unusual values.

Width(mm)/Cross-Section(%) - Rim-Diameter(inch) (e.g. 175/50 13)	/
Width(mm)/Diameter(mm) - Rim-Diameter(inch) (e.g. 210/620 R17)	/
Width(cm)/Diameter(cm) - Rim-Diameter(inch) (e.g. 18/67-17)	/
Width(inch)/Diameter(inch) - Rim-Diameter(inch) (e.g. 6.6/19.5 x 14)	/
Due to a Request from Nicola i did add another Line for older Tire Designationcs from the late 1960's, like 4.75-10.30-15 (Scheme below).
Tire Wall Height (Inch) - Tire/Tread Width (Inch) - Rim Diameter (Inch)	-

You also can check TGM Tire Sizes and if a TGM File uses the integrated Size Multiplier: