what if tire size

2001 cherokee running 275/70r16 tires with 4/10 gears. Question is what would happen if i put the stock size tires back on for the winter (P225/75R15)? How would the gearing affect shifting and such?

What does a 275x70x16 measure out at? Seems like it'd be a 32" or less. It would affect your gas mileage and power marginally, other than that it will be fine. There are numerous people who run taller tires such as 31"s, 33"s on stock 3.55" gears. You're going the opposite way running a smaller tire on 4.10"s. Your acceleration off the line will be awesome, but your top speed may suffer a bit.