The 205 refers to tread width in millimeters. The 75 refers to side wall height, 75% of tread width. So the 215/70 will be a little bit taller.
The 215/70 will be a little wider, not taller. The overall hight will be pretty close to the same, within a tenth of an inch or so.
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!
