I have 20" rims with 275/55/R20 Michelin tires trucks gets around 23-24 at 65mph. The rpms with the 20s is around 1600is at 65mph. Oh 3.42 gears.

Would sticking stock 17" wheels with a stock size tire, maybe a 1/2" taller tire help out mpgs more? Trying to get this truck to 25mpg for bragging rights

Now the wheel would be lighter but the smaller tire would move the rpms up 100ish.

Don't care about city b/c I mainly drive highways now. About 80% highway and 20% city.

 

would'nt a heavier wheel, once at highway speed speed, be to your advantage?

 

Wheel weight wil make zero difference once at speed. The difference in weight is only important when accelerating an decelerating.

 

A larger wheel will turn fewer engine rpm's on the highway which results in more mpg, unless it is lugging and downshifting a lot.

 

I believe stock tire heights are 31.6" and your 20" tires are 31.9". So in reality you will turn less rpm with the larger wheel but it won't be noticeable. I'd look somewhere else for mpg gains

 

no lugging or down shifting! Perfect yall cleared up my confusion. My chrome rims are starting to flake and only have maybe a year left of life so new wheels are in the future. Thinking of switching to the non chrome nnbs tahoe rims. to keep my tires.

I have every bolt on possible, so I guess the only way to get better mpg would be switching to 3.23s, but I think this will bring worse mpg b/c the rpms will be to low and lugging.

Would a low boost system help with mpgs? Still can't make up my mind on which route to go turbo vs supercharger.

 

maybe a supercharger will add enough low end tq to run 3.23s without lugging?

 

Yes, a supercharger along with lower downshift speeds would be good. I tow a big RV trailer and it never needs to shift out of OD. Without the trailer it gets fantastic mileage on the highway too. I run the 1900 Magnusen on a 383.