ClaySlayer

tread pattern makes a difference too...

straightaxle

recap, general consensus is that the weight is likely the biggest factor, although all of them do contribute.

Stock tire weighs about 50 lbs or so, so at what point do you think you start to see a significant change? 65 lbs? 70lbs? 80lbs?

I *think* that anything over 70 lbs will basically be the breaking point.

brucesears

It's a toss up between the two. Either is going to hurt mpg.

remnard

heavier and taller tires will also increase stopping distances.