Downsizing tires effects on fuel economy

[4 tone f250]

I'm thinking bout going down to stock size tires from 315/75r16 and I'm concerned that the smaller tires will reduce my fuel economy I'm currently getting around 18mpg does anyone have any input? Thanks in advance

6.9idi 4sp 4.10rear open flow duel exhaust

 

[itsacrazyasian]

you'll have to slow down on the highway to reduce rpms. Narrower tires will net better fuel economy. if you're really that concerned, go tall and wide. 18mpg ain't bad though.

 

[4 tone f250]

Tall and wide? Like the tires I have now?

 

[IDIDieselJohn]

Skinnier tires will actually up your mpg, by having less rolling resistance....

 

[Fordsandguns]

Tall and wide? Like the tires I have now?

I think he meant to say tall and narrow. I'm not sure what size would be as tall as the 315's and be narrower but it seems like that would be the way to go.

 

[dmaxjoe]

They are getting harder to find, but, I like my 255/85/16's. Tall and narrow.

 

[jwalterus]

I'm not sure what size would be as tall as the 315's and be narrower but it seems like that would be the way to go.

clicky linky ----> http://www.1010tires.com/tiresizecalculator.asp

 

[4 tone f250]

The only tires I've ever found that are narrower but as tall actually taller are qr78-16 but you can't really find em anywhere as far as I know except interco has a set that look like the old buckshot mudders, which I actually have 1 of the buckshot in good shape as my spare, but the interco weight rating is too low my truck weighs nearly 8k

 

[8973]

Skinnier tires will actually up your mpg, by having less rolling resistance....

Less rotational mass as well.

They are getting harder to find, but, I like my 255/85/16's. Tall and narrow.

That's my next tire right thar.

 

[rjjp]

255/85R16 should be the same height of the 315/75R16 but less width, BFG mud terrain are the only ones I've found in that size that's an E rating.
If you want bias ply 9.00R16 will give you a 36" tall tire rather than 35, but still the same width as the 255. 9.00R16 is equivalent to 255/100R16, but Michelin is the only company that I know of making a radial in that size, and the military has them on contract.

Dropping down to stock will probably hurt your fuel economy on the freeway, in town it could possibly help.

 

[Kevin 007]

I have 285/75r16 BFG's on mine. I don't like the width but thats all I could find that is 1.5 inches taller than stock. My RPM's didn't go down much but they did drop a little, anything helps with the t-19

 

[rockbender]

I'd definitely consider something between stock and where you're at now with 4.10's:
315/75R16 - 34.6"
285/75R16 - 32.8" (seems like lots available in this size)
255/85R16 - 33.0"
235/85R16 - 31.7
265/75R16 - 31.7

I went from 315's to 265's for a bit on my van, but didn't like the RPM jump with the 4.10's. I'm pretty content with the 295's I've got now (33.4"). Without an overdrive, I'd look for a 285 that has a bit more of a highway or all-terrain type tread that rolls nicer than a MT.

 

[FORDF250HDXLT]

swap rear axles to 3.55 and run stock 235/85/16 for best overall mileage gains.
the issue with going with taller tires is,it raises the truck which introduces more air under the truck where aero is horrible.
now combined this setup with a custom low front air dam,and you should be able to pop up from 18 to 20+
you should really consider a zf5 or e40d swap too.whatever the cost,if you plan to own the truck and drive often,is payed back in little time at these fuel prices.long gone are the days of driving a truck without over drive.

 

[chvycmnslvr68]

Hi .. I am new on here but have had quite a lot of time playing with fuel mileage and tires do make a lot of difference its been my experience that 235/85R/16 gets the best mileage except for maybe a 7.50/16 which is getting harder to come by ... I too had a truck with 315/75R/16 and when i put them on i lost around 6MPG on highway and about 3 MPG around town .. but its hard to say how much was due to the tires and how much due to the lift (6")... currently I am running my 91 1 Ton dually crew cab 4x6 and am getting around 26 MPG on highway ... but that falls off above 65 mph and my truck doesn't set very low either ... but Ford F250HDXLT is right if your running a 2 Wheel drive you may think about putting an air shield around the front bumper it will make a pretty substantial difference .. I plan on designing a snap-on tarp system for the whole undercarriage of my truck later on once i get all the mechanical problems worked out

 

[itsacrazyasian]

Tall and wide? Like the tires I have now?

Tall and Narrow.

Long day at work. Didn't proofread. Sorry.