2005 DX Automatic

Quick question. My wifes friend has offered us this car for a decent price. I have been driving it the past few days and noticed that the odometer and the trip meter are showing a reading more mileage than what I am showing by using mile markers on the highway as a reference. Could this be caused by improper size tires? Also, the drivers side wiper I replaced the other day, does not fit windshield very well. There are points where contact is not true. I flipped the wiper around and it was worse. Its a 26 inch Anco refill. Any suggestions?? Thanks in advance.

Also, the light for the radio does not illuminate. Is there a fuse for this?