the tire sizes are 205/75 which is 153.75 tall and 215/70 which is 150.50 tall, I get 3.25 mm difference, times two?, for a total of less than 1/2" difference between them for total height but the narrow tire would be the tallest. I hate the metric system!
Converted to Standard, the 205/75 has an 8.1" dection width, and a 27.1" diameter. The 215/70 has an 8.5" section width, and a 26.9" diameter, so there's only .2" difference in hight, but .4" differnce in width, with, as you mention, the wider tire being shorter.
That can even vary depanding on manufacturer and what model tire it is. The sizes are really a nominal size, with rim diameter being the only true constant. To get the actual dimensions, you really need to check the manufacturers specification.
