benbo88

Hey guys,
I`m new on the forum and in need of help/info.
I just change my 4 OEM General Tire on my 20005,5.4,3:55 rear end gear,4x4 super crew for 4 new Michelin LTX AT2 Lt-265-70-17 tires....bigger.(Michelin did not make them in OEM size)
The first thing I noticed is the big change in MPG.I went from 13 MPG to 10 MPG for the same kind of driving.(mainly city driving).I was expecting a little change put not that much.
The other strange thing is that seems like the truck get stuck in 3rd gear.I need to go to 50MPH or more for the tranny to shift in OD mode.It is kindda having trouble finding which gear to select,problem I did not have with the OEM tire.
I`m also pulling a fifth wheel during summer time.I wonder how much my MPG and tranny will suffer with this tire change.
Do you think the tire change in tire size will cause damage to the tranny and can the dealer do some kind or re-programming on the truck.

Any help will be gratly appreciated.

Thanks

Benbo

2005 Black Ford F150 Super Crew
2003 Mazda Protege
1988 Ford Mustang 5.0

rplatt56

bigger tires = less mpg plus speedo is not accurate any more

PawPaw

I'd try a programmer that can adjust for tire height to correct speedometer and adjust shift point's. I have an Edge Evolution in my truck that does both. Also help's when towing.

benbo88

It brings another ???.I checked with my Garmin GPS and if the GPS is right,with my new tires,I have the real speed,meaning I was off with the original tire????So a reprogramming would help????

Benbo

squirrelyyy

it seems all of these truck speedos are off 2mph according to gps's mine was to

onelildude

check out a programmer as stated above. It will help out with your mpg as well as giving you the ability to change your tire size and get your speedo back to normal

NGM

Get a good SCT Xcal programmer. You won't be disapointed. More power and better MPG.

SinCityFX4

^^X2

p3ripperfw

I just find it really hard to believe that that small of a change in tire diameter is causing these kinds of problems....for your gearings your just barely under the gear ratio for optimum gas mileage with your size tire by the chart.

http://www.4lo.com/calc/geartable.htm

I just put 33;s on my truck which was just a tad over 2 inch increase in diameter with the same 3.73 gearing and 4 wheel drive it had and have not had any problems with my shift points or the tranny hunting in and out of gear. I havent filled up yet so dont know what the mileage numbers will be but it doesnt seem to be burning much more if any fuel than it was...of course I do as much highway driving as possible to get the better gas mileage from the larger tires.

Your dealer can reprogram the computer to account for the different size tires and those should be well within the limits of what they can program in. Or if your wanting performance you can do like everyone has said and get a tuner....the dealer will probably charge 50-100 dollars and try and get ya for a ton of other repairs as well so a tuner is really worth the extra cash

benbo88

Is a programmer easy to install or need it be install by a professional???
When you say more power,does it also mean less MPG...usually more HP=less MPG.
Does a K& N air filter really helps power and MPG???

Just love the help I get,thanks guys.


Benbo