hey Lemmts,

The drop in milage may not be as much as the raw numbers.

the increased tire size will cause your RPS to drop by about 6% depending on which Trans and Rearend ratio you have. Or to put it another way, the number of miles that you actually travelled will be about 9% more than the odometer reading unless you had it recalibrated for the new size tires.

the figues I came up with are:

<TABLE style="WIDTH: 541pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 width=721 border=0 x:str><COLGROUP><COL style="WIDTH: 53pt; mso-width-source: userset; mso-width-alt: 2596" width=71><COL style="WIDTH: 48pt" width=64><COL style="WIDTH: 56pt; mso-width-source: userset; mso-width-alt: 2706" width=74><COL style="WIDTH: 48pt" width=64><COL style="WIDTH: 48pt" width=64><COL style="WIDTH: 48pt" width=64><COL style="WIDTH: 48pt" width=64><COL style="WIDTH: 48pt" span=4 width=64><TBODY><TR style="HEIGHT: 12.75pt" height=17><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 53pt; BORDER-BOTTOM: #c0c0c0; HEIGHT: 12.75pt; BACKGROUND-COLOR: silver" width=71 height=17 x:num>235</TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 48pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" width=64 x:num>70</TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 56pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" width=74 x:num>16</TD><TD class=xl28 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 48pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" width=64 x:num="28.952755905511811" x:fmla="=(A1*((B1/100)*2)/25.4)+C1">28.95</TD><TD class=xl29 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 48pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" align=right width=64 x:num="7.5798137624999997" x:fmla="=(D1*3.14159265)/12">7.579814</TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 48pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" width=64 x:num> 3.55</TD><TD class=xl29 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 48pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" align=right width=64 x:num="2.135158806338028" x:fmla="=E1/F1">2.135159</TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 48pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" width=64 x:num> 1500</TD><TD class=xl30 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 48pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" width=64 x:num="36.394752380761844" x:fmla="=((G1*H1)/5280)*60">36.39475 </TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 48pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" width=64 x:num="00.7"> 0.7</TD><TD class=xl30 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; WIDTH: 48pt; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" width=64 x:num="51.992503401088349" x:fmla="=I1/J1">51.9925</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; HEIGHT: 12.75pt; BACKGROUND-COLOR: silver" height=17 x:num>265</TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" x:num>70</TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" x:num>16</TD><TD class=xl28 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" x:num="30.606299212598426" x:fmla="=(A2*((B2/100)*2)/25.4)+C2">30.61</TD><TD class=xl29 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" align=right x:num="8.0127103875000003" x:fmla="=(D2*3.14159265)/12">8.01271</TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" x:num> 3.55</TD><TD class=xl29 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" align=right x:num="2.2571015176056339" x:fmla="=E2/F2">2.257102</TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" x:num> 1500</TD><TD class=xl30 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" x:num="38.473321322823303" x:fmla="=((G2*H2)/5280)*60">38.47332</TD><TD class=xl27 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" x:num="00.7"> 0.7</TD><TD class=xl30 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: silver" x:num="54.961887604033294" x:fmla="=I2/J2">54.96189</TD></TR><TR style="HEIGHT: 15.75pt" height=21><TD class=xl25 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; HEIGHT: 15.75pt; BACKGROUND-COLOR: transparent" height=21>Width</TD><TD class=xl25 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent">Wall Ht</TD><TD class=xl25 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent">Rim</TD><TD class=xl23 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent">Diam.</TD><TD class=xl22 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent">ft.p.rev.</TD><TD class=xl25 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent"> GR</TD><TD class=xl24 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent">GR.fpr</TD><TD class=xl25 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent">eng.rpm</TD><TD class=xl26 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent">1-1mph</TD><TD class=xl22 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent">ODGR</TD><TD class=xl26 style="BORDER-RIGHT: #c0c0c0; BORDER-TOP: #c0c0c0; BORDER-LEFT: #c0c0c0; BORDER-BOTTOM: #c0c0c0; BACKGROUND-COLOR: transparent">OD MPH

</TD></TR></TBODY></TABLE>

 

My calculator put the 265/75's @ 9.9% faster. Which would be good on long, flat straights, but when you get some turns, hills and mountains (or parking garages ) it takes more acceleration, hence, lower MPG.

 

How big of an increase in mpg would a performance chip, a cold air intake, and dual exhaust make? Would it be worth the money?

 

Dual exhaust on a "V" is always worth it. The chip and cold air intake are out of my experience. However, a K&N (or Fram AirHog) filter will help too.

 

The tonneau cover on my truck increased the mpg by 2; but I use 10% ethanol blend and that made it drop back.

 

Has anyone experienced any black soot on the rear bumper from the exhaust? My sister has an 03 F 150 4x2 Auto SWB Flareside with a tonneau cover, and about 55000 on it now. Not sure what gears. Has had it since new. Bone stock except the tonneau cover. She drives about 25 miles one way to work on the freeway. That is most of her driving. She was getting about 20-22 the first year she had it, but now only gets about 16. She says that there is black on her rear bumper from the exhaust. Sounds like a lot of gas is going out the exhaust. Maybe could use the computer reflashed? I don't know. She replaced her air filter recently with no change.

I have a 2003 F 150 4x4 Scab with a 5.4 3.55 LS rear, and I get that with mixed freeway and city. I know that 5.4 will stomp all over that 4.2. I don't understand. Especially since it got so much worse. Don't know if she is driving it harder trying to get V8 performance from the V6 now that the newness has worn off.

Any input about the soot on the bumper would be appreciated.

Thanks

 

I say have it scanned set codes. Change plugs & wires, use some seafoam or other QUALITY injector cleaner. See if her driving habits have changed, or if she's noticed a change in performance.

 

Thanks, I'll get more info from her about it and see if she can get codes pulled.

 

20.8 mpg some city, mostly country roads. What an improvement. But, get my heavy truck in a city, like yesterday, and the mpg is terrible. On some of the slow country roads that are very hilly and you have to stop or move at a very slow speed, I can tell how heavy the truck is. No problem with the power, but this is one heavy truck.

 

She doesn't drive the truck hard. Her boyfriend says she drives like a grandma. The truck has 3.55 gears in it. She said that she had it put on a machine at the dealer a while ago because it was running rich, but I don't think they found anything. I didn't think the first tune up on these new truck wasn't till 100,000 miles. Also, this should have the coil-on-plug ignition, so you need to change the coils with the short plug wire, too, right? Does anyone have anything on the soot coming from the tailpipe? Seems like it is running rich.

 

I drove from Bham, AL to Louisville, KY and then back to Bham.
I was in no particular hurry so I drove about 68-70 mph the entire trip. Sort of "babied it" just to see what kind of mpg I'd get.
Air Conditioning was on probably 80% of the time.

Total trip I got 23.1 mpg!
I think that's pretty darned good for a full sized truck.

Best I've ever gotten.
I guess driving slower makes a difference.

 

Wow, I wish I could get 23 mpg. I usually get around 16 mpg in my 2003 Regular Cab, and that's mostly in the city driving to and from work and school. I guess more highway miles would mean higher milage. I just got the truck in August and haven't had a chance to drive it on any extended trips.

 

I currently own a 2003 reg cab short box 4.2 v6 & my exhaust pipe is always black carbon.I get on it on the highways,70mph.avg.I have 27,000 miles on it,and replaced plugs 5,000 ago.I'm waiting on my v10 to be delivered shortly,but my f150 has never let me down.

 

Drove my truck a thousand miles over the weekend. On one leg it got 24mpg. Most of the trip it got 21mpg to 23mpg. This was my first long drive with the truck, the gas prices were scary......#3.20 in places so I was glad to get the mpg I got. The truck was not fond of long hill climbs, it downshifted. But, it did very well the whole trip. Two days before the trip my battery light was flickering, I have a gauge so I did not think anything was wrong, but brought it to the dealer anyway..................got the truck back 3-days later as something was wrong in the dash and the alternater had to be changed.

 

I dunno about MPG but I know when my tanks filled on my 4.2 I can get up to 582 kms before fill up time