would anyone know just how much increasing the tire size affects the mpg?
she has 285's on her now.i guess it had 245's from the factory.with a 318,i think im getting somewhere around 11 mpg.this has to be the main culprit.
my ram is stock except for a k&n drop in i had laying around.about 72k miles on her.
whadda ya think?

 

look in the door area on the driver side not the door itself but the truck


idk how much it wud affect ur mpg but it wud cause it takes more power to tur those tires

i would think maybe 225's came w/ it thats wut came w/ the 5.9

 

They'll definately affect mileage. You gained about two inches in diameter with the 285's, which has the same effect as in putting in higher gears (numerically lower) in your rear end. It's good for highway cruising, as you'll be turning a lower rpm, but it sucks for around town, because you have to get those bigger meats spinning and up to speed. How much in town driving do you do vs. highway travel?

 

i never thought of looking there.ive looked on the net at various site and got mixed answers.some said 245's others said 225's(which seems really small for such a big truck).

as far as driving in town vs interstate....it depends.when i 1st got the truck,i was workin about 40 mi from home,one way.35 of those were on I-79.thats when i figured out it was 11+/- mpg.
now im working about 7 mi from home and 4 are interstate miles.so it varies from job to job.
i know a gear swap would be the ticket but thats a grand,smaller tires would be the other option but.....i love the look of the 285's(bigger is better) so that,i guess,is really not an option at all.heheh.
all the other things like the air intake,exaust,headers,etc....would prob be great if they were all done at once but it still wouldnt be right.i might as well go for the gear swap to get it back in the powerband where it belongs.make sense?
thanx for the thoughts.

 

not a prob...where i old ya to look for the tire size it tells ya alotta stuff like homuch ur vehicle can tow DOB etc etc

 

Yeah, I'd suggest a gear swap. A grand for a shop to do it seems a bit steep though. You could do it yourself some weeknd if you have the right tools and some patience.

Does your truck run alright except for the bad mileage? Double check and make sure you're truck is running within spec. Take a wiff of the exhaust and see if it's running rich or not, and peer down the intake and see if the intake gasket is shot. Also, when was the last time it was tuned up? A lot of little things can lead up to bad mileage too.

 

im not sure i could tackle a gear swap myself.i have your basic tools but dont you need mic's and special gauges and the sort?i prob have the patience but......id hate to hose the job and be w/out my truck for any amount of time.i know my limitations and i think thats beyond them.theres just some things that i think id be better off letting the pros do.
my truck runs fine.seems to anyway.when you say peer down the intake,you mean take off the air box and open the butterfly valves?if so,i did that when i changed the air filter and it looked clean.by clean i mean nothing jumped out at me.heheheh...except for the field mouse when i popped the hood.that scared the crap outta me.i think that he got in there when i parked in the field at work that day.my dog took care of him though.
i replaced the plugs with some bosch platinums.not the 4 prong ones,just the reg ones.the ones i replaced looked brand new so i think that was a waste of money.was gonna get some wires but i think ill change the rearend fluid before i do.its not missing or hesitating so i think ill wait on those.might do the transfercase fluid then as well.dont know if its ever been changed.im gonna do the tranny too but i think ill wait til my shift kit comes.no sense in doin it twice.
how do you check to see if its runnin within specs?also,where is the fuel filter?id like to change that too but i need to find it first.do you have to disconnect the battery so the fuel dont come squirting out?
thanx man.

 

before you go nuts with a tire swap, i went there already with the dealer when i bought mine. the door sticker says 225/75r16XL. thats a base size. i got a function 14 print out wich is a build sheet direct from the dealer, and it stated that the truck was sold and setup for 265/75r16LT. mine had 225/75's on it and after geting these reports they put on the 265/75's. the dealer nor the factory replaces the door sticker when they install this optional size. go to your local dodge dealer and either talk to service for a function 14 print out, or talk to parts for a star network print out. both will tell you what it came with for tires and that is what the computer is set for. this will help if your doing a gear change to correct the economy/odometer. this way you'll know what you are changing it from to meet your current tire size. also if you dont want to change the rear end gears, the dealer will reset or flash your current tire size into the computer to correct your speedo and odometer.

 

thats good to know.thanx

 

I have a '94 Ram 4x4 with a 5.9, when i switched from 245/75/16s to 285/75/16s i only lost about 1 mpg, but i picked up 3 mpg with the cat taken off and a Cold air intake...