I recently bought a used 2003 HCH with 59K miles on it. I love it. :-) I have been getting 43-47mpg, never below 43 when I tank up, even in city driving.

My car does not have the original tires or tires designed for hybrids...instead it just has regular tires. When I had a mechanic (non dealer but experienced working on that type of car) check out the car before buying it, he said that he would recommend me to buy better tires, and that it would impact the mileage.

What are your thoughts and experiences on this matter? And should I just wait for my current tires to wear out before replacing them (that was what the mechanic recommended)?