Need a little more info such as year, engine, gears, 2wd or 4x4, etc. But firstly you should do a tune up if you haven't already. Such as spark plugs, oil change, diff oil change, tranny fluid change. Just the basics

 

HAve you had it since new, and watch these #'s fall? If so, tune up! recently bought, another vote for tune up, unless you have paperwork show service done before sale. What size tires are you running, which rear end?

 

your 2007 1500 with 33's.. didn't see which engine, but spinning bigger tires with (Probably) 3.55's will eat gas mileage, but your also going farther per revolution from your stock tires, so although your overhead shows 8mpg's add a 10% factor in mileage for the new tires and your probably closer to 10MPG. Did you get a programer to correct speedo?

 

10% is a bit generous IMO. I had 34.6 inch tires on my hemi on stock 20's and the difference was about 5%.

 

its a 07 5.7L Q/C S/B 4x4 Laramie with 33s on the stock 20s

 

There is definitely something wrong then. Go in for a full tune up or do one yourself which is cheaper. Then if you want to help up the mpgs up a little more go to 17" wheels with the same diameter tires, an e-fan, tuner, CAI, and exhaust will all help raise those mpg some but at the cost of all the aforementioned things. But a tune up is your best option. My guess is those spark plugs have never been changed

 

The stock tires are 33" tall on the 20" rims and come stock with 3:92 gears,my 03 hemi with 180,000 miles still gets 11.5-12. something is definitely wrong but i think its probably your plenium gasket.

 

the 11.5 mpg's is alllll city driving, in a small town with more than 10 stop signs on the main road.

 

3rd Gens don't have pleniums

 

I agree with all the above. TUNE UP Time!!! Spark plugs (all 16), fuel filter, air filter, clean ur throttle body, change oil, and maybe throw a bottle of lucas in there. See what that does for ya

 

8 mpg wtf, wonder if they would give you a refund on that fill up....j/k

 

Is there an in line fuel filter on these trucks? My truck gets horrible mileage. About 350km per tank Which is about 220 miles
I've done plugs and keep the air filter clean and oils changed

 

no fuel filter. just a screen mounted on the fuel pump that some may call a filter.