Q:Our 2004 F-150 with a 4.6-liter V-8 and 3.73:1 gears lost mpg when I changed the tire size from 235/70R17 to 265/70R17 (Fuzion LT tire). I was hoping a taller tire would reduce rpm and improve fuel ...

If you've ever modified a car with smaller or larger tires or, perhaps, a different final-drive gear, you've immediately screwed up your speedometer. This is, of course, annoying, but for modern cars ...

Big, chunky, off-road-ready tires have become quite fashionable among truck enthusiasts. The nature of gearing, though, means that owners who choose to increase the size of their tires may have to ...