depends how much fuel your truck uses at whatever loads. For me to work, 1/3rds is 35mph, the rest is 50mph.
Mine's a 1986 SR5 X-cab 22REC EFI and I get the same 31/32mpg at 65mph and 28/29mpg at 75 mph. My truck has a 3.58 rear gear.
That's about how mine is. There is a old highway that I cruise on sometimes. Never any sheriff's around either. I can do 100 mph in 4th I don't have enough power to push 5th lol. Doesn't govern out either. I average around 31 on the freeway. I'm not really in a rush to get anywhere.
That's what the gubmint weenies want you to believe. There is nothing magical about 55MPH. Your mileage will drop starting from 45MPH or even less. 55 was just a compromise between "too slow" and "high mileage". When they discovered that the NMSL (national 55MPH speed limit) wasn't saving much gas (because everyone was ignoring it), they switched their message to, "55 Saves Lives". But THEN, when they repealed the NMSL and most states raised their speed limits back up to 65~70, they found out that, "55 Saves Lives" was BS, too.
I got an average of 23mpg with a lot of heavy, spirited driving, to include 275's on all corners. I was turning 2000 at 60mph. W58 and 3.41/.42's. I think i was turning 2500 at 70mph, been six months since I've driven.
22r/W58/4.56's/25" tall tires. I cruise right about 80 getting in the neighborhood of 18 mpg. I wonder how bad it'll get when I swap the 32/36 for a 38/38.
Man you cruise with some higher RPMs don't ya?! 22r/w55/4.10/26" tires I cruise between 60 and 80 depending on traffic and how lucky I feel with weavin in and out and get about 20
Oh yea, but the mechanical advantage is sooo worth it. There is only about a mile of freeway between my house and work so it's not like I have to be cranking it up for hours on end.