37s and 3:73s

[98chevy2500SS]

Really? That sucks to hear. The salt brine **** that they spread on the roads is just terrible.

 

[Ehall8702]

Really? That sucks to hear. The salt brine **** that they spread on the roads is just terrible.

It's a sand/salt mix so when it sits the sand grinds the paint off and the salt just eats. It pretty bad up here, that's why I figured if I bedlinered it, it's an epoxy and when it starts coming up I should be able to scuff it up and spray some back on and be all good...key word here is "SHOULD" lmao

 

[lubbockguy1979]

Everybody has a different perception. Running a 33 stock gearing and towing isnt a great idea on a 4l60 variant tranny. It becomes a how long will it last. Go to 35 or 37s and the time is faster. I too doubt 22mpg. I find a 88-98 pickup in perfect running condition to be barely adequate. Uch less stepping up to a 35 or a 37. I remember towing 3 horses in a stock trailer from 95-98 in our 94 z71 that was stock. It did the job. But it struggled on any kind of hill drivi g across the flat land of west texas.


But if it were me to be honest. Id regear to 4.56 at least

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[Hutchinson]

Agree fellars,.... my HT383e with 35 BFG AT’s, tuned 0411 PCM, with 3.73 gears gets a whopping 10.4 to 11.2 mpg. I didn’t swap in a lower ring and pinion when I installed the Detroit Helical locker,...sure wish I had. It’s on my list of *hit to do, to finish this build out, just ain’t got round tuit yet. The 3.73 leaves a little bit of haul tater left on the table,....plus dogs the engine at stock 55mph torque converter lock (1600rpm). I used my HPTuners to up all my trans shift points/ TC lock point, plus did all kinds of trans tuning mods to get what I wanted.

 

[Jerry Dickerson]

I am running 343 with 31 in and it done 20.8 mpg... I haven’t even began to bring it around I have 373 and set of 410 so I think I want 33 with 373 and with other mods will see 25 mpg love luv luv my vortec

 

[lubbockguy1979]

I am running 343 with 31 in and it done 20.8 mpg... I haven’t even began to bring it around I have 373 and set of 410 so I think I want 33 with 373 and with other mods will see 25 mpg love luv luv my vortec

Good luck with that. Gearing helps restore mechanical advantage. Larger tires and/wheels though add weight. Tire wheel weight effect you differently then the same additional weight in say the bed. With the right gearing and enough torque down low you might be able to achieve the numbers.

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[Ehall8702]

Good luck with that. Gearing helps restore mechanical advantage. Larger tires and/wheels though add weight. Tire wheel weight effect you differently then the same additional weight in say the bed. With the right gearing and enough torque down low you might be able to achieve the numbers.

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I honestly think the only thing that's been an advantage in my truck is the fact I have light 20" rims, ALOT less rubber than a 35 on a 16 and a **** ton lighter. I'm gonna swap gears soon, still haven't gotten my bl lift on it the 37s mounted , just to see what it's gonna do. Have to go pull my "new" trans Tonite and put it in this weekend , that's priority since no reverse when the snow starts flying isn't an option.

 

[Ehall8702]

Good luck with that. Gearing helps restore mechanical advantage. Larger tires and/wheels though add weight. Tire wheel weight effect you differently then the same additional weight in say the bed. With the right gearing and enough torque down low you might be able to achieve the numbers.

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Stock except no cats and throttle plate shaved ( whatever aluminum baffle ground off) and vortec box removed on 33x12.50r20 on 2014 GMC Denali oem 20s and all highway numbers came to just under 22mpg, that's running 80-85mph non stop for almost 5 hrs. Half tank (21gal ) and 255 miles later. Didn't use speedo ( used GPS cause speedo is off) , didn't use odometer ( used GPS also, but not because I was already aware odo was off too just because gps is easier).

 

[98chevy2500SS]

I am running 343 with 31 in and it done 20.8 mpg... I haven’t even began to bring it around I have 373 and set of 410 so I think I want 33 with 373 and with other mods will see 25 mpg love luv luv my vortec

When you go larger on tires, you won't get better mpg, it will get worse. Don't know how you will achieve 25 mpg, when I had the same setup with 3:73s and 33s and got 12.5 mpg at best.

 

[Ehall8702]

When you go larger on tires, you won't get better mpg, it will get worse. Don't know how you will achieve 25 mpg, when I had the same setup with 3:73s and 33s and got 12.5 mpg at best.

Either ur truck just dogged the f out or you got bad o2 sensors or something is waay off. With bad o2s and 31s on a bone stock 98 Yukon consistently gets 16.8mpg, that's with 317k on it. If I'd ever get off my butt and put the new ac Delco o2s in it'd get 19ish I'm sure. Only code my truck throws is a "cat performance' code, and that's because there is no cats on it. When a vortec is running right and all sensors are functioning properly they get pretty good gas mileage. Ppl neglect to replace 02s and wonder why u get really poor gas mileage, then after replacing them ( and not with a cheap one that barely works) the fuel trims need to be reset ( sometimes called "block learn"). And yes the speedo is calibrated on the Yukon, I can calibrate it with my zues scanner. Point is, if ur fuel mileage sux, check codes and monitor o2 performance and see if they are doing thier job properly, it's the number 1 killer of fuel mileage on these thing, followed closely with dirt air filters, dirty maf , dirty throttle plates and fuel filter.