11screw50

While you are right that tread width and section width generally differ, the ASPECT RATIO has nothing to do with the tread width as it is a measure of the sidewall height as a percentage of the section width.

Do your same search on TireRack but use Bridgestone Revo2's and check the tread width of 275/55/20 (9.2"), 275/60/20 (8.7") and 275/65/20 (8.5"). You just chose to use an example that supported the incorrect statement that you had made.

Royderjd

alright so everything I found out yesterday. Since i have a 2010 ford, you can only get your tire size adjusted at the dealership. however they are only 4 selection of tires size in the computer. you cant put in whatever size you want so i would check to see what tires you can change to that are in your PCM if you want different tire sizes.

@ http://www.discounttire.com/dtcs/infoTireMath.dos you can plug in any number size tire and do the math to see if they are close or not. i found out that the factory 275/55R20 is very close to the other factory setting in the PCM of 275/65R18. only off like +.39 at 75mph.

with all that being stated I'm looking into getting rid(sell) of my current tires the 275/65R20(f-250 Tire size) http://www.discounttire.com/dtcs/fin...=TXLINT&cs=275 and replace them with some 275/55R20 street tires. then before i goto Alaska I'm going to get some new wheels and tires in 275/65R18 since you can get A/T tires a lot cheaper in that tire size.

mikeyfitz

I say screw that, buy a tuner and get some big boy tires! You'll get better mpg as well, well minus big boy tires lol

Ecko150

Mines gets 14 hwy as well, crappy but i figured it came with the territory

Ecko150

This is my rig

Royderjd

what size tires do you have now and what size tire does the truck specify?

I'm rough hearing people are getting 18mpg on 4x4 trucks with light truck tires made for the road. not the AT tires. thats with the 5.4 the ecoboost i hear gets more on the highway

gDMJoe

I didn't just choose to use an example to support my statement ... And using your supplied example ... The lower aspect ratio has a wider tread width.



BTW ... All of my tire selection examples are done at TireRack.
.

Ecko150

my tires are 305/55/20, i believe stock are 275/65/20....

Robob

Also if the truck has never had spark plugs done and its 70K plus miles you could consider that, I noticed a slight gain in mine after doing plugs/air filter. I get 16 city 18highway with my 5.4 on 3:55 gears

Ecko150

is 3.55 gears the norm for fx4s..i have no clue what mine is.....also how hard was it to do your plugs on the 5.4..