Replacing tires with wider tires.

I did exactly what you are thinking about doing. I noticed quite a bit mroe low end power with the shorter tires. The handling was better, RV was a little bit lower. Did not notice a change in fuel mileage, but I only drive 65 anyways to avoid problems. I wore them out and the best deal on tires at that time was the 8R 19.5's. So I switched back and absoultely made the wrong choice. I lost a lot of power. I would do the switch again in a heartbeat. The speedo will read about 2-3mph off, barely enough to notice or worry about calibrating.