The OEM Bridgestone B381's are definitely the tire you want for the best mileage. I lost about 5MPG when I replaced the OEM tires with something else. I went back to the Bridgestones for the 3rd set. Now I have a couple of cheapies I'm gonna throw on the front for the summer then buy a new set of 4 B381's come winter.

That's the plan anyway. Unfortunately they are up to $93/tire at the tirerack.com. And I don't see them coming down anytime soon with the cost of oil going up, up and away.

Yeah, I would keep what I had until they wore out and then replace them with the Bridgestones.

WARNING!

I don't know where you're at, but my experience has been that while the Bridgstone's are great for mileage, they are horrible in the snow. Just sayin...