[SilveradoMike]

Hello, Im Mike. I am a contracted parcel carrier driving my own vehicle and paying my own fuel. My vehicle is a '99 Chevy Silverado with a 4.8l v8 and a 5 speed manual trans with 4wd.
I'm looking to get into hypermiling as much as is reasonable for my situation. Like no engine off coasting (to much cargo weight for that) and shutting off engine while idleing more then a minute or so (restarting about 75 times a day would kill my starter and charging systems). So a little more detail on the truck. Its a bone stock truck in the single cab long bed configuration. It has an A.R.E. Commercial +4" shell on it (shell is 4" taller then cab non tapered) The truck currently has LT245/75/16 E rated tires on it but the door tag calls for LT 265/75/16 C rated tires. After some reseach I found that going down a weight rating but up one size will net a loss of 4lbs per tire. And I found that my rear axle has 3.73 gear ratio which is great for pulling my 700-1500 lb load daily but terrible for highway speedsy.I drive ~200-350 miles per day (including commute) 90% of my daily mileage is rural windy roadd. A few things are unchangeable in my scenario tbe truck the load the miles. The ine that that can be changed is slight aero mods (I was thinking a deflector from my cab to the shell) And the nut behind the wheel can be changed. My fuel current fuel mileage numbers are slightly off due to wrong tire size but for the last 3 months I've averaged between 17-18.5 mpg. Id like to push to the 25ish or higher range. I plan on replacing my tires with the correct size next week along with ordering a scan gauge from here. Any suggestions to consider? Thanks everyone.