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31K views 32 replies 24 participants last post by  Garrell Chiasson Sr  
#1 ·
What kind of mpg are you guys getting with 35s on stock 20s? I know mpg is goin to go down with a bigger tire just wanting to get an idea before I pull the trigger on new tires
 
#4 ·
I wish I got 13. But then I can't see worrying about MPG when you buy a Hemi and then outfit it for off road. It's either what you want or buy a Prius.
 
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#11 ·
14 Express RC 2wd 6spd with 3.92's. 4.5" lift with 35x12.5's Cougaria MT's on ballistic 20's. I have a avg of 14.3 in the last 2 tanks- hand calculated but the evic is close. At least 75% stop and go with lights and traffic and maybe 25% on the highway usually between 70 and 75 mph. Speedo reset but never installed a tune yet. Actually better than my 13 4x4 CC ever got with 285/60r20's.
 
#13 ·
Lifetime overall with 5k miles is 16.2 and on the open road I get 20-21 with no problem, but I have the 8 speed tranny with 3.21 gears too. 35" toyos with a leveling kit. The 3.21 gears don't bog it down like you might think, the 8 speed makes up for the high ratio with the first two gears pretty low.

Like others said,with a close to 400 HP motor and a 4x4, I am more than happy to get 16 mpg!
 
#18 ·
I've got 295/65R20 (35+) on stock 20s, and the 5.7L with 3.21 gears. I wouldn't let 3.21 stop you from upgrading your tires. Really not sluggish like some people are reporting. Not sure if it's mostly heresay from those who assume 3.21 would lag a ton...but mine still has plenty of pep. Really happy with ride quality and look of 35s with my Zone 4" lift as well.
 
#21 ·
@contederv, happy I went with 295/65r20s. With a 4" lift, no spacers required and no rubbing. I did not drive my CC very long with the stock 33" before I upgraded to 35s, but she still moves out just fine.

BTW, after mynlift/tire upgrade...I did get the Hypertech to calibrate speedo. Not sure howuch this made a difference to synch the shifting better compared to other reports; since it was calibrated before i picked her up from lift shop.
 

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#23 ·
35's are terrible for highway mileage. Most 35" tires are E rated (12-ply) so they are heavy and ride like a donk'd out 90's caprice.

Mine got 12mpg highway with 3.92 and 35's. I ended up going back to 33's because between the mileage drop, the harsh ride, and the road noise from M/T's, I couldn't stand to drive it.
 
#25 ·
Got a few data points from a recent trip. Overall, better than expected. Sticker standard is 15 city, 21 hey and 17 mpg average for my Hemi 5.7L with 3.21 gears. Bottom line is the average is suprisingly netting 16 mpg with 4" lift and 35s. City was 13 mpg (-2 mpg), while HWY miles are highly dependant on speed.

@ 60mph - averaged 20 mpg (after 55 miles)
@ 65mph - averaged 18 mpg (after 161 miles)
@ 68mph - averaged 17 mpg (after 248 miles)

These data points were only after 250 miles of driving; but seemed pretty consistent. Plus route was actually pretty hilly with final destination about 3km higher than starting point. Includes a few stops to McDonalds drive through and a gas stop. Sweet spot for best mileage seems to be around 60mph, averaging a surprising 20 mpg! But kick it up to around 70 mph (typical highway speeds), and you'll likely be close to 16-17mpg.

Used Hypertech to calibrate speedo, so not sure how accurate this is...
 

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#26 ·
No issues with E rated AT tires, Rancho QL's set at #6 front, #5 rear, rides better than stock. 15.5 MPG with 3.92's and a mix of 75% fwy, rest is city.
I'm also testing different combinations of engine timing to see what the truck likes, lost 1mpg adding 2* more timing to the factory map, so now testing about 1.5* less to see what happens.
 
#27 · (Edited)
I run a 3 inch level (which is essentially a 1 inch lift) and 315x70s (which are essentially 34s). For me the mileage difference with the level and tires was virtually negligible. It was once I removed the front fascia where my mileage plummeted.

Note that I run midgrade gas. The tildes (~) are the EVIC's calculated average - the rest were manually calculated by averaging 3 fillups.

My truck used to have 3.55 gears before I switched the front diff. The transmission shifts fine until its under load (interstate speeds or towing), in which case I just leave it in 4th.

With 4.11 gears I'm at about 1800rpm in 6th @ 60mph, and ~3000rpm in 4th @ 75mph, which keeps the engine in its happy place to maintain speed without hunting gears regardless of load.

What I couldn't stand, and what made me swap the front diff, was the offroad performance - the 65RFE has a somewhat tall 1st gear, so even in 4LO you can't really crawl. Many of the trails in my area are narrow, have steep descents, and are shared by ATVs - so without good gearing you'll be flying down these hills, and forced to ride the brakes the whole time. Adding larger tires does not help matters. Switching to 4.11 helped a bit, but I think be much more happier with a 4:1 transfer case.
 
#28 ·
35" Toyo MT's with 4" lift, 3.92 rear end and mixture of highway and city I get ~16L/100kms
 
#31 ·
I have a 2004 Dodge Ram 2500 with a 5.7 hemi, I would like to put long tube headers on in the future and 35’s. I’m a high school kid getting like 13mpg around town and 15 on the highway on 33’s. I work a decent job and save my money so I care about mpg but I also am in a debate. Would it be worth it to put 35’s on?