Shawn,
215/75 will be much taller and have a larger circumference than a 205/70 tire. To keep things close, I would think you would want a 215/65. Also, I don't know about the width. I have not heard of anyone using a tire wider than 205 on our standard rims. I don't know if there would be any interference with the syspension, body, or exhaust. I also don't know if the rim would securly hold the tire. The tire manufacturer should be able to tell you that.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420