The formula for calculating tire dimensions
The dimensions of a 235/35-19 tire are 9.3” wide (section width) & 25.5” tall (overall dia) The section width is 235mm wide (There are 25.4mm to an inch)
185mm divided by 25.4” = 7.28” (section width)
Multiply 7.28 (section width) by .75 (aspect ratio)
7.28 x .75 = 5.46” (section height)
To find overall dia
Multiply 5.46 (section height) x 2 then add rim dia
5.46” x 2 = 10.92” + 14.0” = 24.92” round out to 24.9” (overall dia)