Diesel Place banner

MPG Change when tires change from 245's to 265"s

4K views 15 replies 16 participants last post by  MKAH 
#1 ·
How much, if any, should I expect my fuel economy to drop when I change out my stock 245's for 265's? I just don't want any surprises? Does this throw the DIC off if you recalibrate for the larger tires? Thanks
 
#2 ·
After almost 6 years on 265's, MPG change was minimal if any. That was with one LB7 and 2 LBZ's. All my trucks averaged around 18 or so pretty conistantly, always hand calculated, when going from the stockers to the 265's.

If you are using a programmer to recalibrate for the 265's, your DIC will probably be off anyhow, though your speedo will be correct. Even with the stock 245's with a programmer, the MPG on the DIC will probably be off.
 
#3 ·
It wont change milage much at all, your dic isnt that accurate to start w/(mine isnt), but recalibrating it would help to keep it accurate,
 
#7 ·
Just Asking

How does one go about recalibrating the dic for those adjustments ?
DIC= (DECC= Doesn't even Come Close):)
It wont change milage much at all, your dic isnt that accurate to start w/(mine isnt), but recalibrating it would help to keep it accurate,[/quote]
 
#6 ·
I doubt you'll see much difference. Calc it by hand before you change tires for awhile, then after the 265's, also calc by hand using the correct adjustment for tire size ( miles X 1.039 I think ).

I get about 16 in town and best hwy was 22, with the 265's. I changed my oem 245's out at 500 miles, but I was getting 16 in town, too.

IMHO, the 265's are the perfect size for this truck, with an A/T tread.
 
#10 ·
I doubt you'll see much difference. Calc it by hand before you change tires for awhile, then after the 265's, also calc by hand using the correct adjustment for tire size ( miles X 1.039 I think ).

I get about 16 in town and best hwy was 22, with the 265's. I changed my oem 245's out at 500 miles, but I was getting 16 in town, too.

IMHO, the 265's are the perfect size for this truck, with an A/T tread.
X2, right on the money as mine did. I changed the tire size at 24k when the tires wore out and put on 265's. I have been getting 14-16mpg around town with warm-ups and stop light traffic. My best was also 22mpg on a trip. All done by hand calculation. The formula above is also correct too.
 
#9 ·
I lost 1-2mpg
 
#11 ·
x3 I never noticed any real difference on mine either. Like they said above, make sure you hand calc and compensate for the difference in tire size. I usually get around 17-18 highway and 14-16 in town, before and after the tire swap.
 
#12 ·
my truck was getting 17+ mpg i put a set of 265 75 16 mastercraft ct's and im only geting 15 mpg. I had the speedo reset by my friend that works for the local gm dealer with a tech 2 scan tool. I guess maybe i need to get a programer on it. my fuel filter also has 5k so i could have got some crappy fuel
 
#15 ·
i towed alot and lost about .5-1 mpg loaded but gained 2-2.5 on the highway empty. I also had 235/85s so they are the same hight but not as wide. If i stayed under 70 i was getting 23+ hand calculated( i know no ones gonna belive this but i monitor it on a spreadsheet for my buisness)
 
#16 ·
I put my 265's on after only a few hundred miles so I really don't have a good idea of mileage on the 245's. My speedometer is checked with radar is now very close (+/- 1 MPH). Mileage varies, depending on how I drive.

Freeway:
55 MPH (who drives that slow?) 22 MPG
65 MPH 18 to 19 MPG
75 MPH 16 to 17 MPG

Downtown driving
Ranges from 13.5 to 15.5

Towing 6,000 travel trailer
60/65 MPH 13.5 MPG mostly mountain driving
60/65 MPH 14.5 flat freeway driving

In a nutshell, your driving habits will yield the best return on mileage and tire wear. I know, I wore out the first set of Toyo 265 AT's after only 25,000 miles. No burn outs, racing or power braking, just aggressive acceleration and hard stops. This truck sure is a lot of fun. :eek:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top