As tempting as it is to jump to LRR tires right away, if the tires you have are usable, you're probably better off costwise to run the existing tires until they need to be replaced, then replace with a carefully chosen tire.
On Tire Rack, when you bring up a list of tires, click on the "Specs" tab to see all the sizes that tire comes in. You can then see the diameter and revolutions per mile for different sizes and see which other sizes would probably fit. The
General Altimax comes in a bunch of sizes, so it's a good one to look at.
They come in 205/50-16, 205/55-16, and 205/60-16 sizes for a choice of diameters. (Go to
this link for a quick tire size comparison tool.)These aren't LRR tires, but once you find sizes that would fit your wheels and give you the overall diameter you want, you can search for tires in those sizes. For instance, I found
36 LRR choices for 205/55-16.
Kumho eco Solus LRR comes in a bunch of sizes, including 185/70-14 for less money and less weight.