small block strokers

I get the same or better than a friends brand new Silverado when cruising on the highway , I usually measure it like a Semi in time , the last 3 years when traveling cross country I got 2.5 hours per 40 litres no matter what speed I travel at so I generally try to take advantage of that , this year I've gone to a bigger tire so hopefully I will get closer to 3 hour per 40 litres , that all translates to @ 10.5 gallons per 2.5 hrs = 4.2 gallons per hour divided into the speed of somewhere between 55 and 80 mph or 90-128 kmh , hoping to make that 3.5 into the speed with the new wheels and tires . confusing enough for ya eh ! LOL .