Drastic increase of gas mileage on my F 150

[Tom F]

With all the gas milage stuff going on I decided I'd try to increase the milage on my 94 F 150 with the 300 cu inline six. Seventy Five thousand miles ago while driving from Home to Monterry Mexico I averaged 17 mpg driving 75 mph. The truck looked pretty nice back then with a 100,000 miles on the odometer (see picture with chromies on it). As of last week it was getting 12 mpg driving 65 mph.
I drive out to my son's place every day which is ten miles from my place which isn't very far but it adds up. So this week I lowered my speed to 45 mph. One of my rear tires was leaking air (has 4 or 5 plugs in it) I decided to change my tires from P235 R 70 15 to 35X12.50R15LT. The larger tire is about 8 inches taller.
Now I'm sure some of you will question if the F 150 has enough guts to run them big tires, well it's got the 4 speed with overdrive and quite often with the stock tire size I would start out in 2nd gear, shift to 4th and then into overdrive.
I put the tires on and it drives great, looks a little funny (see picture), and low gear is low enough. Just driving along with the other traffic it looks like my speedometer is off about 5 to 8 mph.
Now I'll be driving at around 38 mph (which will actually be 45) AND I JUST GOTTA HAVE AN INCREASE IN MILEAGE.
I'll let everyone know exactly how much better it is.
My son said I was crazy but that now the lights shouldn't shine in any ones eyes.