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Got a questions for all that are running the stock size 265/75 R16 tires out there. For anyone who has changed from the stock rugged trail to an A/T have you noticed a difference in gas mileage? Just wondering. I switched from the long trail to a 265/75 R 16 M/T and I've lost quite a few mpg. I travel alot and kinda miss the mileage I got cruisin' on the old tires. Thinking of going with a A/T and keeping the M/T in the garage for special occasions like after it rains on the farm! Just wanted some opinions before I make a change.
Thanks.
 

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I did all sorts of experiments and what you are thinking of doing is what you should do. A 285 75 16 BFG AT weighs in at 82 lbs on the rim, a factory tire on rim about 62. Anyways, it's the weight that matters, go put 10 or 20 lbs of water in a bike tire and see how easy it is to get rolling and stop. When I get a chance I am going to BFG AT on stock rims and save my big ones for occasions where they might work better. I'd never buy that size again now that I have. It was a solid 4 MPG Ave loss in MPG. Yes I use a scan gauge, yes I recalculated it, yes I got 400 MPT before and with larger tires solid 280 to 290 Miles Per Tank. Yes I tried it on same exact 2K mi trip in similar temps with same gas stops at same pumps, and same results. Now a days, at over $3 a gallon, I'm stupid! I need a sign! MC
 

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Dang, I'm getting just 14 MPG with the stock tires making gentle starts - with mud-terrains I'd be getting just 10 MPG ... no way. I've been using a ScanGauge the last two weeks to confirm the "wonderful" gas milage the X gets. I drive 100% in stop light to stop light traffic to work and that's eating the milage like a son of a gun.

A second set of tires sounds interesting ... wonder how long it would take at a 4 MPG loss to pay for a $600 set of rims ... off to calculate.

10/14 * $3.25 = $1 ... about 6000 miles.

(sold)
 

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I'm running the stock size Firestone Destination A/T's, and it's prob. a fluke or something, but on the last two tanks I've averaged 18 mpg. Most of my driving is about 5 mi. to work and back (10 mi. round-trip). That's taking the mileage after fueling and dividing by no. of gallons needed to top off. With gas @ 3.40 here in MI, I'm making it easy on my wallet by filling up with around 1/2 tank left. It's still around 50 damn dollars, though. The X is an '05 with 20k miles on it, with a K&N drop in, no other mods to the drive train, and the 2 in. lift with spacers/shackles.
 

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I'm running the stock size with BFG AT KO's and I have not seen any change in my MPG and all I do is city driving. I average about 15-16 depending on traffic with all the mods listed below.
 

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Just swapping the stock tires for an AT in the same size is unlikely to affect mpg much at all. But like MC says, the weight is the issue. Look at tirerack to compare the weights of tires. I know the BFG ATs are not that much of a jump. But the differences can be huge. In 285 75 16s, the Toyo MTs I was looking at weighed 12 lbs. more than the BFG MTs I went with. For five tires, that's 60 lbs!
 

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A 265/70R16 Long Trail (stock on S) supposedly weighs 36 lbs.
That size in a BFG A/T is 51 lbs
The BFG A/T in a 265/75R16 (stock size on OR) weighs 51 or 54 lbs
The BFG A/T in a 285/75R16 weighs 57 lbs
All of these numbers are from tirerack.com
So, simply going to the A/T is a big hit in weight. Going up to the larger size doesn't increase weight as dramatically, but the moment of inertia increases since the major weight (tread) is further from the center of rotation. I'd therefore expect a hit on MPG around town by switching to the A/T and another hit going to the 285s. For purely highway driving the larger tires have a theoretical advantage. None of this considers the gearing effects of a larger tire.
 

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kneebuster said:
So, simply going to the A/T is a big hit in weight.
Good point. I didn't realize the numbers were that different. Clearly, the ATs are a big jump up in terms of durability, and thus weight.
 

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usmc xterra said:
...A 285 75 16 BFG AT weighs in at 82 lbs on the rim, a factory tire on rim about 62. Anyways, it's the weight that matters, ...

...When I get a chance I am going to BFG AT on stock rims and save my big ones for occasions where they might work better. I'd never buy that size again now that I have. It was a solid 4 MPG Ave loss in MPG.
I can see where the increase of close to 20 lbs (per tire), going from stock tires to the 285/75-16 AT's can cause a big hit with fuel economy. But, from what I see, the weight difference between the 285/75-16D AT and the 265/75-16D AT is only 4 lbs. I can't see where just switching to the 265/75-16 AT would give you much of an improvement in fuel economy.

I think you have to look at the total configuration of the truck, such as the overall weight...including mods, any mods or changes that effect the aerodynamic drag of the vehicle and of course driving style and driving conditions. Almost all mods that we perform on the X to make it more off road capable will have some detrimental effect on fuel efficiency.

Rob
 

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i am getting 13.8 according to the gauge in the dash of my SE. that is mostly in the city. however, i got arougn 22 on a 300 mile trip mostly on the freeway and some on the highway. i am on the stock 265 65 17 tires. might i addthat i have a pretty heavy foot. :)
 

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I'm averaging 17 mpg with 285/75/16 BFG A/T's. Last week I decided to put it in grandpa mode and got 19 mpg out of a tank driving 60 instead of 75 on the hwy and putting around town. My cousin did the same on his '04 trailblazer with 265/75/16 BFG M/T's and only got 15 mpg. I'm impressed with how economic the Xterra is considering the wind drag and tire size, especially for how powerful it is when you do stomp on it.

I'd like to see what going to a larger wheel would do. Going to a 65 series on an 18" rim would probably only make things worse though, because the tire weighs 5 lbs more and I don't think wheel weight really makes much difference. Anybody out there running off road tires with bigger wheels?

From TireRack:
265/75/16 BFG A/T's weigh 51 lbs.
265/65/18 BFG A/T's weigh 56 lbs.
 

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I was getting around 13 for the longest time then I changed my diff fluids and now I'm getting 16 or 17. I also noticed no difference at all with my 285 MT's on S wheels rather than 265 grabbers on steel wheels. On the way to tenn me and mcampana used the same amount of fuel and he is running 265's.
 

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cincinnati_xterra said:
I was getting around 13 for the longest time then I changed my diff fluids and now I'm getting 16 or 17. I also noticed no difference at all with my 285 MT's on S wheels rather than 265 grabbers on steel wheels. On the way to tenn me and mcampana used the same amount of fuel and he is running 265's.
Wait a minute ... not so fast! :)

Changed your differential fuild to what?
 

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PaulXyZ said:
cincinnati_xterra said:
I was getting around 13 for the longest time then I changed my diff fluids and now I'm getting 16 or 17. I also noticed no difference at all with my 285 MT's on S wheels rather than 265 grabbers on steel wheels. On the way to tenn me and mcampana used the same amount of fuel and he is running 265's.
Wait a minute ... not so fast! :)

Changed your differential fuild to what?
X2
 

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I think he changed his differential fluid to new, clean, adequately topped off normal fluid.

But unless you're doing donuts for hours, would diff fluid really affect gas mileage appreciably?
 

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d-rap said:
I think he changed his differential fluid to new, clean, adequately topped off normal fluid.

But unless you're doing donuts for hours, would diff fluid really affect gas mileage appreciably?
Thats what I was thinking. I just did it as regular maintance and thats all i did and now im getting 17 mpg. I havent changed my driving style at all so who knows. I just put royal purple gear oil in.
 
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