Got to http://tirerack.com
They have all kinds of info. If you go with a 215/65/15 you will have a wider tire with better handling than you'd have with 205/70/15 tires. At Tire Rack take a look at the specs of the tires you're interested in. Some of the 215/65/15 are just about the same overall diameter as the 205/70/15 H/T's.