bigger tires=better gas mileage?

[Can30Diesel]

Another small piece of the puzzle is weight, steel rims are heavy. I moved to Aluminum rims and I noticed a little difference in response with my truck. I'm singing the 410 3000rpm blues too, but I can tow pretty much anything and thats what the truck is for.

 

[Wicked97]

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
235/85-16 7.9in 15.9in 31.7in 99.7in 636 0.0%
285/75-16 8.4in 16.4in 32.8in 103.1in 614 3.5%

i really cant say that would be a lot of difference, being the height of the 285/75r16 is only 1.1 inches taller, cause you would still divide that by 2 to get the height gain on the truck.

It was 150 rpm so I guess its not that much. Been a couple years. I went from a 31.2 inch tire to a 33.1 inch tire and probably added 40 lbs a wheel.

 

[bagpiperjosh]

If you put larger tires on around town you will inhale fuel and realistically, most folks spend a LOT more time on side streets than they realize It ends up taking a whole lot more fuel to get all that extra rolling mass in motion, and a lot more brake power to get it stopped THink of larger tires as adding 4 extra heavy flywheels. Yes they are great at storing energy once you get them going, but it takes a lot to get there and then once you get all that energy stored in them, it takes a bunch of energy to counteract the energy stored in them to get them to stop.

If you try to tow with larger tires you will really take a hit. BEst bet is to add an overdrive or Brownie. I have the best of all worlds, a full deep reduction range, stock range and over drive range ( double OD) with the ability to split all gears.. With a 4.10 rear I went from a best 14 mpg ( usually worse ) to 18-20 empty , and over 11 towing HEAVY ( better depending on the trailer )

what is a brownie?

 

[FORDF250HDXLT]

larger tires won't be doing your wallet any favors lol.
for those revving with the old school direct drive transmissions......it's time to upgrade.the fuel savings $ for a good deal on a used zf5 could just be refunded @ the pump inside just a few oil changes......after that,it's pure savings.

im 1350-1400 ish rpms @ 45 mph in OD.

 

[bagpiperjosh]

larger tires won't be doing your wallet any favors lol.
for those revving with the old school direct drive transmissions......it's time to upgrade.the fuel savings $ for a good deal on a used zf5 could just be refunded @ the pump inside just a few oil changes......after that,it's pure savings.

im 1350-1400 ish rpms @ 45 mph in OD.

So when people say " put in an od" they mean do to a zf5 swap? Theres no way to "add a gear" to a trans? Sorry ifthats a stupid question

 

[dgr]

They could be talking about a 5 speed or an actual 2 or 3 speed auxiliary transmission like a ranger or gear vendors or brownie.

 

[RLDSL]

what is a brownie?

A 2, 3 or 4 speed auxilliary transmission , pulled from an old either semi truck or large mid range dump etc. you wind up with an extrshifter to fool with ( just like the old big trucks with twin sticks )
They do not have synchros so they do take a bit more skill to drive. I have a 3 speed 5831b Spicer in mine giving me a 5x4 arrangement , or 15 forward and 3 reverse gears

 

[bagpiperjosh]

A 2, 3 or 4 speed auxilliary transmission , pulled from an old either semi truck or large mid range dump etc. you wind up with an extrshifter to fool with ( just like the old big trucks with twin sticks )
They do not have synchros so they do take a bit more skill to drive. I have a 3 speed 5831b Spicer in mine giving me a 5x4 arrangement , or 15 forward and 3 reverse gears

that sounds like a nightmare to install

 

[PwrSmoke]

RLDSL is right. Overall a five speed or an overdrive (or a 5-speed AND an overdrive) with 4.10s is the best combo of performance and mileage. If you can afford it.

 

[bagpiperjosh]

oh, i also looked on my driveshaft and i saw this E3TA4602 TA DANA

so what rear end is that?

 

[The Warden]

oh, i also looked on my driveshaft and i saw this E3TA4602 TA DANA

so what rear end is that?

What code shows on your build sticker?

 

[bagpiperjosh]

What code shows on your build sticker?

31

 

[The Warden]

My '84 book ('83 should have used the same codes) shows a Dana open axle, 3.07 gears, and 6250 lbs capacity. IITC that should be a semi-floating Dana 60...do you have hubs/axleshaft end caps sticking out from the brake drum a few inches?

The semi-floating Dana 60 is a rare bird especially behind a diesel (it's more of a light-duty F-250 thing), but I've seen a couple on '83 and '84 trucks, so I can say with authority that they do exist...even though most semi-floating axles are 5-lugs and found on half-tons.

Full-floating axle:

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Semi-floating axle:

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[bagpiperjosh]

My '84 book ('83 should have used the same codes) shows a Dana open axle, 3.07 gears, and 6250 lbs capacity. IITC that should be a semi-floating Dana 60...do you have hubs/axleshaft end caps sticking out from the brake drum a few inches?

The semi-floating Dana 60 is a rare bird especially behind a diesel (it's more of a light-duty F-250 thing), but I've seen a couple on '83 and '84 trucks, so I can say with authority that they do exist...even though most semi-floating axles are 5-lugs and found on half-tons.

Full-floating axle:

You must be registered for see images attach

Semi-floating axle:

You must be registered for see images attach

links not working for me

 

[FordGuy100]

I'll keep rocking my T-19!

Bigger tires wont help fuel mileage. Taller tires should in theory help at highway speeds. If they made a 255/85/16 A/T style tread it would be the best choice.