Gas mileage experience with 205/60R15 tires?

I replaced the oem Integrity tires with 205 miles on them. I think I may have filled the gas tank just before I did that but really can't remember for sure. Anyway, I had driven a friend's Prius with the stock tires for a week before getting ours . His car at the time had 6k miles on it and we averaged about 47 mpg around here in the mountains of Western N.C. I'm sure his tires were inflated to whatever the dealer set them to though I don't know what that was.

Our car with Michelin Pilot Exalto A/S 205/60/15 is getting 46 mpg (calculated) but I have been taking many short trips lately which really seem to hurt the average. I did see 52.3 mpg average on I40 with 2 bikes on the hitch mount rack behind the car. I have the Michelins set to 40/38 right now. The car has 1500 miles on it.

I have absolutely no regrets with these tires. Should they wear out in 20k I might think again though. They are rated at 45k. They are very quiet, smooth and handle great. Even though I live in the mountains, the car most likely will not see much use in the snow. I have a 4 wheel drive for that if needed.

One thing I did notice is acceleration off the line is just a bit slower, perhaps due to the extra weight of the tires. Also, the car doesn't seem to roll as freely on moderate downhills. The tires are obviously of higher rolling resistance. Neither issue is a big deal.

I am a pretty conservative driver but safety is a big concern for me. I had some difficulties with the handling of the stock tires on the mountain roads and wet traction is important. I think the Exalto solved both problems and is quieter and smoother too.

Hope that helps.