FlatBlack XD

First of all, I understand that going to bigger tires and ATs will decrease MPGs, so that is not why I am posting this. I mainly just want some clarification.

I have a 2010 SCrew 2WD 5.4 V8, no level. I went from stock Michelin LTX A/S 265/60/18s to Cooper Discoverer AT/3 265/70/18s and absolutely love the look, still no level. My truck honestly looks amazing while still keeping a stock look to it. Minimal road noise, I've been driving without any music to see if I can hear them, there is a small amount of noise, but honestly I think about 1/4 max sound of music will completely block it out with or without windows up.



With that said and why I am posting this is because I am some-what confused, or maybe I am not and I just need affirmation.

So because of the increase in tire as well as going from stock Michelin LTX A/S', I was expecting about a 1MPG loss, maybe a little more during city driving as the tires are heavier and have a higher rolling resistance, which in turn causes my truck to work a little harder to get it up to speed. I got this number by comparing the loss of other people with larger E-rated tires who lost up to 2-4 MPGs depending on the tire/type. With all of that said, and fact that I haven't had my truck reprogrammed/flashed for the new tire size, my MPG average setting in my truck will be off because both the odometer and speedometers are off, right? I know that my odometer/speedometer are off as per other posts and common sense, but I am just educating myself about the MPG Average.

Like I said above, the main reason why I am posting this is to just get confirming/clarify some things for me. There have been other posts but with this information I can help aid some other people who are looking to do the same as me but also have some questions.

Thanks in advance for your time and reading my post.

Here are some more pictures, I'll try to get better ones. Let me know if any of you want some different angles.

McCarthy

Yes, MPG with be way off unless you get the speedo re-calibrated with a tune or whatever.

FlatBlack XD

Great, thank you.

I probably did not need as long of a write-up as I did but I didn't want to leave anything out ><.

Thanks again.

McCarthy

No problem.

codeblue48

just take a ride down the highway and download a free app on ur phone to use as an odometer. I have an iphone and I think I used an app called "Speedometer" but it also gives you an odometer. Compare what your phone says to what your truck odometer reads. You will find that you are actually travelling further than what the truck odometer is telling you (which you already are aware of.) Then just multiply whatever that difference is and you will get your real mpg. For instance, my odometer is off by .04%. If my truck odometer reads 100 miles, I then take 100x.04 and get 104miles. Then take 104miles and divide by number of gallons used. voilà! Hope this helps.

FlatBlack XD

Alright, I will. Thank you for your reply!

I did test the traveling further than what my truck odometer is telling me today with a 12 mile trip. My truck said I only did exactly 10 miles. I'll do this tomorrow as I'll be driving it a little more and should be able to figure out the real MPGs with your method.

I haven't been driving that much and my alignment may possibly be off with the new tires. Although I never really read anyone else having issues with alignment after new tires, maybe I have a "rare" case? I'm getting mild steering wheel shaking that was non-existent before the tires were put on Thursdays at highway speeds. I'll get my alignment checked on Monday to see if it is off at all.

f6bits

According to that tire calculator, you can divide your MPG by 1.068 (slight loss), or multiply your miles by 1.068 (slight gain).

Whenever I get new tires, I get an alignment. Heck, that's only every 3 to 5 years, so it's well worth the $75 (or whatever) to make sure everything's aligned.

FlatBlack XD

What would dividing or multiplying my MPG or miles by those amounts give me? Real world MPG and real world miles?

If what I said above is true, then that means that I lost close to 5 MPG from my tire upgrade which is outrageous because I know about 100 members who have upgraded to 33s on 20s with LT tires and still only lose about 2-3, maybe 4 at most depending on offset.

I'm just trying to understand what that is supposed to give me.

f6bits

However you calculate your MPG, you'll have to divide your answer by 1.068.

So if you filled up with 10 gallons and your odometer says you went 150 miles, you get 15MPG, but then you have to divide 15 MPG by 1.068 to get your actual MPG of 14.04 MPG.

FlatBlack XD

Oh ok, I apologize. Thank you for the clarification.