You could go to a 265/70/17. They are an inch or so wider and just slightly smaller in diameter, about 1/4" if I remember correctly, not enough to worry about the speedo.
It's a popular size tire too, so it's easy to get. That's the size that came on my Dodge Cummins in load range E.
275/70r17 is another choice. Maybe harder to get, and a little larger in diameter. But it should fit without rubbing and only a little error in the speedo.