I was just told by my dealer that I need to replace my rear tires. Currently I am at about 35,000 miles (is this about right?). A friend of mine told me that hybrids use a special low resistence tire and I shouldn't use just any tire if I want to maintain my good gas mileage. Is this correct, or can I get anything that is the right size (such as what they sell at Costco or what not)? Also, what are your recommendations about getting just the two rear tires replaced versus replacing the whole set. Thanks for your help.