lost 20% fuel economy by stepping up one size on my tires. is this normal.

Hello to all from the frozen Canadian rockies. Im wondering if anyone has seen the same results... Back in September i jumped on a sale for some duratrac's. I have a 13 limited taco with the cladded 18"s. The stock rubber was 265/60r/18. After lots of research and cross refrencing of many threads here in Tacoma world's site i found i could safely jump up to a 265/65r/18. They are just slightly over the recommended 3% increase in up sizing without a lift. They sit a tad bigger than 32". So my milage has instantly dropped as one would expect. But my drop seems a bit large for such a small increase in tire size. After break in i was averaging 600km's or 375 miles a tank. With the new duratracs im lucky to break 500k or 312 miles per tank. Ive boosted my psi to 36 pounds to try to improve my situation but hasn't really done anything. At 29psi they seemed almost to soft or low on pressure. I understand i had highway rated tires before and they are going to help with efficiency. But my god ive lost 20% of my mpt. So i guess my question is... is anyone else having these same results. The mechanics at the dealership thought it was a bit much but couldn't help. Could it be an ecu adjustment. Thanks for reading and any input would me awesome!!!

 

Are you accounting for the extra distance you're traveling but not showing on the odometer due to the longer distance the larger tire travels? What was the weight difference between the old and new tire? Winter blend gas? Extended idling/warming due to cold weather?

 

That's seems a bit higher than my drop was when I went to my Duratracs (LT265/75R16) from my Dunlop AT20 (P265/65R17). I was averaging 21 to 22 mpg pre-lift and tires and am getting ~19 now. I run mine around the same pressure (maybe 40-ish) but didn't see a whole lotta difference at the low 30's.

Keep in mind that cold weather and winter fuel will make your mileage considerably lower; I'd say my average drops at least 2mpg in winter versus my highs in summer.

 

The LT tire is a truck tire and is heavier than the tires you replaced. Even though its only a few pounds per tire, it's unsprung weight and can make a substancial difference in performance and fuel economy.


I found a article on Tirerack that talkes directly about this.

http://www.tirerack.com/wheels/tech/techpage.jsp?techid=108

 

How might one recalibrate? Ive only heard of dropping 2-3 hundred on an aftermarket device to adjust speedo. Also might add that the tires were installed in september while temps were still in the 70's. Also adding that my truck has always been parked in a parkade with temps warmer than most peoples houses. She never idles.reading that article double taco once the minions go to bed. Thanks for all your input guys. Helps with looking at it when its not just one guy problem solving or understanding the situation. These duratracs might be costing me an extra 10 bucks every time i fill up...

 

How

 

For me the +1 sizing actually seemed to make the speedo/odo correct based on GPS and speed trap signs. That said the OP is running a size above mine.

Yep, I knew the LT's would knock economy going into it but I'm happy with the tradeoff's. The EBC kit I picked up over the holidays should help with stopping the mass; I don't mind the losses of the line since she's not built for speed

 

You did not say what the 20% was of. If you were getting 16 mpg before a 20% drop you would be 12.8 MPG or a 3.2 MPG loss wit new tires. With the added weight and design of the tire that could easily happen.

 

Here is how.
http://www.autoanything.com/performance-chips/61A3757A0A0.aspx

 

Hypertech makes a calibrator for our trucks, I've had it for a few years and it works great. The software is fool proof you simply enter in your old tire size and your new tire size and hit enter. The module itself simply installs behind the gauge cluster and it comes with a USB cable that you can keep stashed under the dash for easy access with a laptop.

 

So i was getting around 18mpg before the duratrac's now im getting around or close to 16mpg . The 20% was based on my average miles per tank. It is actually a bit higher than 20%

 

You cannot figure MPG by miles per tank. However if you WERE getting 18 before, and now around 16 you only lost about 11%, not 20.

If you are not going to re-calibrate you odometer then use a GPS to keep track of your miles driven and check the actual MPG at fill up with the amount of fuel purchased.

 

Lower than 20%. Your odometer is underestimating how far you have traveled per gallon of gas. Just how much is hard to say as it probably wasn't spot on to begin with.

 

From summer to winter i lose about 10% MPG, so i go from 525km to 475km on a "full" tank. When it's snowy / i have to use 4wd, my mileage drops to maybe 400km per tank. Stock tire size.

 

You should be happy, I'm around 350km/tank on 265/70/17. I would sell my soul for 20mpg

 

So is my only option to re calibrate my speedometer to spend 250 dollars on an inline device? You would think with all the mods being done with lifts, gearing and especially tire upgrades that this speedometer adjustment might be built in. I bet a good percentage of new tacos being sold now have had lifts and 33-35" rubber bolted on before the owner has gotton the keys.
So after checking the tire calculator i have lost 3.3% tire revs per mile/km. So my 500km/313miles is looking more like 516.5kms/323.3miles with the increased tire size. So overall im down roughly 80kms /50 miles per tank.

 

Wouldn't you're mpg average be more correct based on average distance per tank of fuel? I still dont fully understand how my limited taco does no fuel consumtion info for me. My chevy express van gives me all sorts of numbers and averages. The taco does nothing? They stuff a jbl sound system in the truck and get to stick a limited badge on it.

 

Huh

For $200 I'll pass

 

Well, I have to ask. Why did you purchase a truck that doesn't meet your expectations.

Please tell us. We gots to know.

 

Soon you'll figure out all the other common amenities the Tacoma doesn't have.

Heated mirrors? nope
Height Adjustable seats? nope

Toyota made the Limited to compete with the upscale full-size trucks. Unfortunately they did a half ass job about it adding pieces that already existed and some lame chrome bits.

The word on the street is that the 2016 Limited will have features closer to the 4Runner limited.