i have a 2005 dodge ram reg. cab 4x4 with 35in. tires. i put a flowmaster 40 series turndown and it gave me better mpg from the 11.5-12mpg for a while but now it has dropped to 10mpg. why would this be? because i dont drive any different than before. any ideas? and i am thinking of getting a spectra cold air intake. would this help or hurt my gas milage? i am a pretty average driver accept when im goin to fires. and my 35's wont be on much longer and im gonna put 265/70/17 tires on. any idea on mpg when i do that?

 

Cold air intake will defiantly help your mpg's. I had one in my old blazer and it jumped up a lot. I just got one for my 2500 ram and it is helping. I only got it today but the average mileage went from 10 to almost 12. Plus it has more horsepower and you can really tell the difference in the acceleration. Also gives it a nice deep sound. K&N CAI ran me $242 on ebay...

 

Did you notice the drop in MPG after you put the 35's on? If so you may need to correct for the tire size or calibrate your speedometer. Any time you change tire size, the perceived mpg changes unless you correct in some way.

265's will help with MPG due to lower weight.

 

make your own cai and save like 200 bucks. ton of threads on here on how to do it, that is if your more for performance than looks.

 

i had the 35s on before the exhaust. and i am goin by miles traveled divided by how much fuel is used.

 

Hmm I wonder how often u guys change out fuel filters?

Im thinking if a guy upgraded spark plugs and wires might help with the mpgs also.

I was pussyfootin around town yesterday and avg 14.7 mi/gal in town. Not too bad for the hemi i guess.

Also wouldn't bigger rims and tires help with mpg? More weight but less revolutions of the wheel would help drop engine rpms a little helping fuel mileage?

 

fairly common to lose a mpg or two with a Flowmaster muffler, they sound very good but the chambered design is among the most restrictive out there.

https://dodgeforum.com/forum/3rd-gen...mparisons.html

CAI is only going to be as good as the most restrictive part in the intake/exhaust. It don't matter how much/fast you take in air if it can't be scavenged/released just as fast...