Big Tires= Big Fuel Consumption????????

[1985K20]

Ok i know lots of yas are running big blocks and diesels in your rigs...here's my question!:Is bigger cubic inch engines absorbing the crazy fuel milleage increase with big tires(33's and over)???

friend of mine told he seen very little difference with small or big tires with a 6.2 diesel...

I know my little 305 burns just about twice as much when i put my 35's on, but buddy's telling me he sees no difference small or big tires with a 366 BB..

Are they bull$h*tt*ng me or is it true?

 

[tRustyK5]

I get 16.5 mpg on the freeway pushing 39.5" TSL's with my 6.2. That's without an overdrive, and from what I have heard from other 6.2 owners that are turning about the same rpm's as I do their mileage is about the same...maybe slightly better. The 6.2 doesn't really seem to care about the larger tires, just the actual rpm's. If I could get the rpm's down I could pick up a few mpg.

Rene

 

[blackblazer717]

i always say its in the gearing!!!

 

[4trolls]

Im running 39.5s with 4.10 gears and a stock 350 with no noticable change in mpg in my 78 suburban

 

[dyeager535]

My dads K20 is running a 454 with 33's, and it gets the same in the city as it did with the 350. Freeway is about 1-2MPG less. 4.10 gears, gear vendor overdrive.


Lots of factors, contact patch, tire diameter, vehicle height, etc.

 

[joez]

With my 6.2, i dont notice much difference between the 33" radials and the Q78's. Its still slow as crap and gets at or over 20 mpg depending on how i drive it.

 

[r_pogo]

Tire Pressure & MPG

On a road trip it might help increasing the tire pressure a bit.

On several cars/trucks I've owned I have had a 1-2 mpg increases by bumping up the pressure 4-5 or so psi over the sticker while still under the maximum indicated on the side of the tire. This also make them run a bit cooler and wears more on the center to compensate for wear on the edges that happens in all the city dirving.

 

[82K5_6.5L]

i just went from 33's and stock 3.42 gears, to 35's and 4.10's... man what a difference!! more power, better mileage, better everything!!! and thats with the 6.5L, it feels alive again!!! probably averaging around 16-17mpg..

 

[Zeitler]

i just went from 33's and stock 3.42 gears, to 35's and 4.10's... man what a difference!! ..

i wonder how i'm gonna feel after this:

from 32's & 2:73 to hm have not decided what tires yet but 4:56 gearing

problably gonna feel like i'm still in 1st gear!!!

 

[k20]

I went from 33x12.50s(measured out at about 32) and a 350tbi, went to a 496mpfi and 35x14.50's, and my mileage went from 8 to 10-11.

 

[Bhintz]

i just went from 33's and stock 3.42 gears, to 35's and 4.10's... man what a difference!! more power, better mileage, better everything!!! and thats with the 6.5L, it feels alive again!!! probably averaging around 16-17mpg..

exact same thing here

 

[Ned Kelly]

454/TH400/4.10 diffs/39.5's I get 10-11mpg hwy (best at about 2200rpm) and 7-8mpg in town.