The sidewall of your tyre will consist of a series of numbers and letters, the numbers and letters will let you know the size of the tyre, the load rating and speed rating of the tyre. Along with this you have a series of other numbers that wont really mean anything to you so just ignore them for now. The numbers and letters represent the E marking and the production date of the tyres. The information you need from the tyre is illustrated in the image.
A - Tyre width as shown in images as 205
B - Tyre profile / height measured in mm 55
C - Rim size R16 measrued in inches
D - Load rating 91
E - Speed rating as ilustrated in V
F - Brand name