33's and 12.5 MPG..What are you guys getting??

[Lowboy44]

I should have went with the bigger lift and 35's if I knew ahead of time that my MPG would suck so bad going 1" larger in tire size.

I have 285 70 17, CAI, TB spacer and exhaust..no tune currently getting about 12.5 HW..Can this be correct..I was getting 17 mpg when I had 265's

What do you guys get and what suggestions do you have? I know the BB tune would help but they say 1-3mpg after tune..my luck is I would see 1 mpg better for $600 bucks :-(

Thanks for your help

 

[ccapehartusarmyINF.(ret)]

a 1 " difference in overall diameter would definatly not have that drastic affect on fuel economy normally it would have so little an affect youd probably never notice you should
i would say its the CAI they will lean out your fuel trim and what happens when your mix is really lean the PCM has to ad more fuel to keep the proper mixture and your fuel economy suffers so when you get your tune your PCM is reflashed so that it does all of that much more effecient
also id probably ditch the throttle bodey spacer they are pointless for electronic fuel injection

 

[clandr1]

My Yukon is 100% stock (2WD). I get 15mpg average on a tank according to the DIC, but when on the highway, it'll read 20 mpg when i'm doing 65 with the A/C off.

5.3L

 

[Lowboy44]

Thanks for the info..Im going to put stock intake back on and see if things improve

 

[ccapehartusarmyINF.(ret)]

yea id just try the stock intake see if your fuel eco improves if it doesnt you mite have other problems
you can also reset your pcm by disconnecting the battery it will relaern all your driving habits and fuel mixture etc

 

[01Konvict]

That seems very low! My highway with 33s is 16.75-17mpg and 12-14 city. I think part of the mpg loss is fuel tune from stock intake but more so applies to the weight of the tires. My guess is the 285/70R17 are a class E tire which is 10 ply vs stock class C at 6 ply. These heavier tires weigh about 30 lbs each more than stock weight. I may be wrong but have seen loss in mpg due to class of tires due to weight.

 

[ccapehartusarmyINF.(ret)]

yeah i agree it can affect your fuel economy but not that much from what ive learned its usually overall diameter

 

[scoobyxj]

Also don't forget that with the larger tires the speedo isn't right, and in turn that's going to throw any, and every mpg calculation you try to do using the odometer, or the DIC out the window. The only way to get an honest check is to use a GPS to track, and record your miles driven to each tank.

 

[Lowboy44]

thanks again for the info..im running BFG MT's which are 6 ply tires..headed into garage today to put stock intake back on..stay tuned

 

[podwarrior63086]

I'm running 33x12 with 6" lift and with edge tuner on economy I get 18 to 20 mpg on highway.


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