Tyre size conversion US / European system
The sizes of some tyres are indicated in inches in accordance with the American measurement system.
It reads : 32 x 11.5 R 15 LT - total height of the tyres x width R diameter :
- 32 : Tyre diameter in inches.
- 11.5 : Tread width in inches.
- R : Radial tyre.
- 15 : Interior tyre diameter or rim diameter in inches.
- LT : U.S. term for "Light Truck".
The conversion into the European metric system is simple enough since :
1 inch = 2,54 cm
For example the US size 32 x 11.5 R 15 corresponds to the following size in Europe :
Sidewall height :
( (heightUS x 2.54 - diameter x 2.54) / 2 ) / (widthUS x 2.54) = height in %
((32 x 2.54 - 15 x 2.54) / 2 ) / (11.5 x 2.54)= 74%
Then, you only have to round it up to the closest existing height : 75
Tyre width :
11.5 x 2.54 = 29.21 cm = 292mm
You then have to round it up to the closest existing width : 295mm
The diameter stays the same.
The US 32 x 11.5 R 15 size corresponds to the European size 295/75 R 15