Answer:
The dimensions of the tire are 190/75-15.
The first number is the width of tire in mm, here is 190 mm
The second number is ratio between sidewall and width of tire in %, here is 75%
The third number is diameter of wheel in inch, here is 15 inch or 15 x 25.4 = 381 mm
Then, we have:
1. Â The width of the tire is the first number: 190 (mm)
2. The length of the side wall = width x ratio = 190 x 75/100 = 142.5 mm
or 142.5 /25.4 = 5.61 inch
3. The diameter of the whole tire:
D = diameter of wheel + sidewall x 2
  = 381 + 142.5 x 2
  = 666 mm or 666/25.4 = 26.22 inch
Hope this helps!
:)
