I've been keeping track of my gas mileage for awhile, since 2 or 3 tank fulls before I went to 285 BFG's.I need to keep track of it, my Co. pays my gas tab & making the tire change I wanted to see the change,(didn't want the boss to ***** about the mileage drop), anyway, I've noticed that its been dropping like a rock. Stock I was getting 18.5-19.5 mpg, after the tires I lost a little, not as bad as I thought it would be, but over the last few weeks it seems to be around 14-15 mpg,???? Driving the same roads the same way. I'll update with my tank-by-tank mpg later today, out of the log I keep, so you can see. Would oil change & plugs make much of a difference?? I have 16,500 miles on it now. Was reading spark plug threads & got me thinking, time to swap out the plugs. Any sugg. on type of plug? Should I run Syn. oil?? Even though I don't pay for gas I would still like to see better mileage. Any thoughts??