Tire size for best fuel economy

My 07 4x4 V6 long bed has 265/65 17 inch tires and is getting 15 MPG in gentle driving (slow acceleration) which includes 80% on interstate to work. It has 40k miles on it. I would like to improve my gas mileage by increasing my tire size but I don't know how large to go and how much lift that would required. Has anyone done this? The truck has a lot more power than I need so I'm not too concerned about loosing power. I don't want to make a mini-Monster truck out of it, but would be pleased if I got 3 - 4 more MPG. I also want to be able to put chains on the front tires for when the going gets really tough, cause the front is where the chains do the most good. Last Christmas we had to go through 12 inches of snow and ice in the mountains of North Carolina.

To get 3 more MPG it seems the larger tires would have to have a circumference 20% greater than the current tires. To get a 10% greater circumference (or 1.5 MPG more) would require a 325/65/17 tire - and that tire may not exist or even be practical. So this idea may not be practical, but i wanted to ask here.



BigRedWeather

 

In addition to getting further with each turn of the tire- you've got more rubber to move (more unsprung weight) and the sum total will be a decrease or at least a static gas mileage performance

 

Tire chains on the front wheels?!?

I'm 100% positive they go on the back wheels. You want them on your drive wheels.

 

Yes, and no.

If you're always in 4WD, I would recommend putting them on the front as well as the back, so you have greater steering control, as well as greater grip to push yourself through.

Chains just on the back are useless if you're only pushing yourself straight with the wheels locked to one side.

 

Correct. but if in 2wd on a rwd vehicle, the chains on the front aren't doing much good without chains on the back unless maybe you are turning a corner. But you obviously have to get to said corner first..which would require traction on the rear wheels.

 

You're right. I'm going by what the OP's intentions are. And likely, he'll have his vehicle in 4WD by the time he gets to actually need the chains.

 

Too many topics in one question. Let's throw out the tire chains and focus on the gas.

Yes, you roll farther with a larger diameter tire, creating a net higher (numerically lower) total gear ratio. However, any tiny incremental advantage this gains you is *totally* lost by the increased energy required to get those larger, heavier, tires spinning, and by their increased rolling resistance.

Haven't you looked on TW at the 10,001 threads decrying the gas mileage *lost* by folks who are running larger tires??

No, if you want the best gas mileage, go down to the 245/75R16 tire that's stock on the 4x4 work truck. Choose a tire with a low rolling resistance tread designed for high mileage.

 

x2!

and as far as the chains go.. chains go on the drive tires, whether it's front wheel drive or rear... (RWD, chains go in the back.. FWD, they go in the front.. 4x4.. you CAN go on all 4, but why... you've got 4wd... lol)

 

I don't want to have an argument with everybody about this. I'll just share what my experience has been.

My mother's house is 1 1/2 mile up a mountain in North Carolina on a gravel road. From her house she can see Mt. Mitchell, the tallest mountain east of the Mississippi. In recent years she has been getting 12 - 18 inches of snow at least once a winter. Last winter, on top of heavy snow we had an ice storm that took her power out for 8 days. With that mix on the road our 67 Jeep Truck 4x4 that goes "anywhere" and a 95 F150 4x4 wouldn't make it up the hill. With chains on the rear they did better, but still wouldn't make it up. With chains on the front both of these trucks performed like tanks and went up and down as often as we needed.

To make it up the hill we didn't need more power, as in 4 Wheel Low, we needed more traction, which is what we got when we put the chains on the tires that have the most weight on them. In addition, having more traction on the tires that did the steering enabled us to move the trucks to the part of the road that was most advantageous. With chains on the rear we could push the truck, but we couldn't steer it adequately, because 12 - 18 inches of snow was being pushed in front of the truck as if it were a plow. Sure, we could throw a load in the back of the truck for more weight or traction, but this still wouldn't let us steer adequately, and we needed the back of the truck for other loads.

That's my experience. I'm sure yours is different. Each of us will do what works for us.

One last thing. I got my 07 Tacoma 4x4 with radial (40k miles on them, the tread as about 40% of new) a few weeks ago. Christmas weekend I felt sure I was going to need chains to get up to my Mother's house with 8" of snow on the road, no ice. They would have gone on the back because there isn't room in the wheel wells on the front (the tires are 265s.) That bugger went up without a problem and no chains. I was very impressed. Plus we went over two major mountain ranges on the way home, where states of emergency had been declared, with no problem. Having ABS that really works is a great advantage over the 67 Jeep and my 97 F350 (that's where "BigRed" comes from. My Tacoma is Li'l Red.) The F350 has ABS but after this many years the ABS doesn't work consistently. This is the 5th Toyota I have owned. So far, I am very pleased with this truck.

Have a wonderful and safe New Year.



BigRedWeather

 

how is there even a question about this?

4x2 = chains in the back

4x4 = chains on all tires

if you're going to be going through enough snow and ice where you will need chains you should already have tires that are decent in snow

 

Your only getting 15 mpg? I have an 07 DC with 35" nitto mud grapplers getting between 14.2 and 15.8 mpg mostly highway. Truck is new to me, so I'd bet gears were done, but not sure about the rest.

As far as chains go, it's best to run on all four if it's rear or four wheel drive.

 

As for the question, the weight of the tires will make a significant difference in MPG. If you go to tirerack.com and into the "specs" on each tire they list weight. There is sometimes a drastic difference in tire weight for the same size tire. The extra 5-20lbs per tire adds up. So if you could find a tire that was taller yet lighter than stock, you should get better MPG (in theory)

 

Might as well throw in my two cents. In Alaska I run winter tires and summer tires. If you can go that route (changing out your tires for the season...I keep two mounted sets for all my vehicles)...then I highly recommend Bridgestone Blizzaks Stud-less tires for winter. My first 8 yrs up here I ran studded tires in winter, mainly Hankooks. This year, after reading numerous reviews and an in depth study by WA DOT, I switched to the Blizzaks, they beat any other studded tire I've ever run.

Like I said, just my two cents worth based on a 42 mile (each way) commute from Palmer to Elmendorf AFB in Anchorage for the last 9 years with 7-8 months of winter driving every year. Hope it helps, the reviews were on Tire Rack and if I remember correctly I found the WA DOT study by "Googling" Studded Tires vs Stud-less Tires, or something like that.

 

get class s for up front. tire cables are really cheap and work great. If I had chains on i had already put it in 4wd and I chose to put the cables on the front. I wore mine out last year so I'm getting new ones. cables up front and chains in the back. I agree with you one chains in the front bc of the wieght and steering. I hope to have an aussie up front this winter too.

Too those that said if you have 4wd you don't need chains your wrong. I've seen 4wd look like a sports car on ice or in really deep snow.

as for the mpg your way off on your "bigger tires = more distance with the same amount of power"

engine has to work harder to turn the bigger tire.
you've lifted the truck now and your aerodynamics start going out the window (the very small bit of aerodynamics your brick had already if any)