I have a 2005 Ram 2500 5.9l with 48re with the following upgrades, AEM cold air intake, 5in turbo back exhaust, Smarty set on level 3, Centerline wheels w/ 325-60-18 toyo AT's. The truck gets approx 15-16 mpg city 15.5-16 mpg hwy hand calc. My question is the tires and wheels killing my fuel mileage and does anyone have simular setup with better mileage? Any input would be much appriciated.

 

Yes. The large tires are hurting your mileage. I only have 305's and I get 14 mpg city and 16 mpg highway, so I don't think you are doing too bad.

 

When I bought my truck it just had 285's on the stock rims but they were mud terrains and when I switched them over to the 265 bfg ruggeds I gained 1.5 mpg. They look like turd tires compared to the ones on there but my truck rides a lot better and these tires don't seem to wear at all. I'd definately say it's your tires/wheels hurting your milage. By the way I get about 18 city, and 20-22 highway if I can keep it under 65mph.

 

in the November 2008 issue of Consumers Reports magazine
they have a fairly large pickup/suv tire test
of 'all terrain'
'mud & snow'
and 'winter' tires

one comment that they make
is that they ran a MPG comparison test using their 'mule'
( Chevy 1500 Silverado pickup )
between the lowest rolling resistance tire (Goodyear Wrangler SA-R)
and the highest rolling resistance tire
and found over a 2 MPG difference
with no other change but the tire swap