Real World MPG with 5th Gen?

[Quentin]

Q,

Nice chart! I like this. While I understand why it is, could you tell me how you got 80ft for the 285/70s and the 1.035 number? Also, mine are 275/70s, so I assume are only a tiny bit bigger than stock...probably 1/2-in taller (guessing) when inflated to 43psi. I have not done math like this since college! Sure would be nice to get a chart on here showing such calcs for various diameter tires for people to use. Actually one with actual tire diameter intervals in 1/4 inches would be sweet!

On a side note, it seems like everybody who is doing his/her own MPG calcs is getting higher values...is this indicating inaccuracy of the onboard calc?

So, a 275/70-17 tire means the sidewall height is 275mm * 0.70 = 192.5mm. The rim height is 17" (431.8mm). Total wheel and tire diameter is 816.8mm (32.16"). Wheel circumference is 100.97". OK, now run the same numbers with the stock 265/70-17. You'll see a small difference in total circumference. Divide that difference by the wheel circumference of the OEM measurements and that gives you your mileage percent difference.

There are a couple web calculators online that will tell you how your speedometer and rolling circumference changes with stock and new tire sizes.

 

[poolzer]

Ive been consistant with 17 in/around city and 22 on long drives. Drove 500 miles today through NW Nevada, NE Cali and southern Oregon through hills and all and stayed between 21-22. Just hit 14k miles.

 

[Snooperstyle]

So, a 275/70-17 tire means the sidewall height is 275mm * 0.70 = 192.5mm. The rim height is 17" (431.8mm). Total wheel and tire diameter is 816.8mm (32.16"). Wheel circumference is 100.97". OK, now run the same numbers with the stock 265/70-17. You'll see a small difference in total circumference. Divide that difference by the wheel circumference of the OEM measurements and that gives you your mileage percent difference.

There are a couple web calculators online that will tell you how your speedometer and rolling circumference changes with stock and new tire sizes.

Thanks for that. Here is one such link I just found. Tire Size Calculator

Looks like for every 100,000 miles, stock 265/70s are turning about 1075 more miles than 275/70s...a very minimal difference. I think that would equate to a difference in MPG of about 3/10ths of a MPG...

Based on this, and the fact that other people with heavy E-rated tires are still getting good MPGs, looks like the Baja Rack is the bigger culprit!

 

[Quentin]

Thanks for that. Here is one such link I just found. Tire Size Calculator

Looks like for every 100,000 miles, stock 265/70s are turning about 1075 more miles than 275/70s...a very minimal difference. I think that would equate to a difference in MPG of about 3/10ths of a MPG...

Based on this, and the fact that other people with heavy E-rated tires are still getting good MPGs, looks like the Baja Rack is the bigger culprit!

While adding substantial frontal area and definitely increasing the drag coefficient, I'd say you are right about the baja rack. This is assuming that you don't do much stop and go. If all your trips are basically getting those big rollers moving and maintaining that speed until you reach your destination, you aren't suffering too badly from the add'l rotational inertia of the heavy tires. If you do a lot of stop and go, even at highway speeds, you are going to notice having to get those heavy guys moving each time you leave a stoplight and get up to speed.

 

[blacksmithdog]

I noticed I took a 1 mpg hit when I went from the stock Bridgestone HT's to Michelin LTX AT2's.

 

[SeattleMike]

Thanks for that. Here is one such link I just found. Tire Size Calculator

Looks like for every 100,000 miles, stock 265/70s are turning about 1075 more miles than 275/70s...a very minimal difference. I think that would equate to a difference in MPG of about 3/10ths of a MPG...

Based on this, and the fact that other people with heavy E-rated tires are still getting good MPGs, looks like the Baja Rack is the bigger culprit!

I took a big hit when I added my rack. My summertime mileage (running the AC, E-rated Duratracs, Perkins rack with wind deflector, fully loaded with gear) on the highway was in the 18/19 mpg range and the city mileage was deplorable. Storing the rack added 2 mpg, turning off the AC added another 1 mpg, and unloading the gear added another. I'm going to experiment with a new deflector and see if it helps any.

 

[ssmathis]

I've been averaging around 18.5 in mixed driving all over 6k' feet in elevation too. Not to mention our freeways are 75mph as well.

Scott

 

[simple06]

I just put on some BFG KM2's 265/70/17 which of course are stock size. With a combo of city/highway driving it looks like I may have lost about 1 MPG. I was usually in the mid 19's before. I'm taking a long road trip soon so it will be interesting to see what effect the heavier tires will have on straight highway driving. In the past with stock tires I got 22 MPG or just a little lower.

 

[iDRiVaT4R]

I remember when I had my stock tires, I was using a GPS and the speedometer on the 4Runner was at least 2 mph faster than actual at 60 mph. IMO stock tires are under size to help make you think your getting better mileage than you actually are. Smaller tires also give the vehicle better acceleration times. Remember this is just MY OPINION, not proven or anything.

I had my scangaugeII in my 2008 Tacoma, had 285/70R17 KM2's, Short tube headers, Flowmaster, AFE intake, Budbuilt Skids, etc and the scangauge was dead accurate, I was averaging 13-14 mpg. So my 4Runner averaging 15-16 on the on-board computer doesn't seem too far off.

 

[Quentin]

I remember when I had my stock tires, I was using a GPS and the speedometer on the 4Runner was at least 2 mph faster than actual at 60 mph. IMO stock tires are under size to help make you think your getting better mileage than you actually are. Smaller tires also give the vehicle better acceleration times. Remember this is just MY OPINION, not proven or anything.

I had my scangaugeII in my 2008 Tacoma, had 285/70R17 KM2's, Short tube headers, Flowmaster, AFE intake, Budbuilt Skids, etc and the scangauge was dead accurate, I was averaging 13-14 mpg. So my 4Runner averaging 15-16 on the on-board computer doesn't seem too far off.

Speedo is commonly incorrect. Almost every manufacturer reads higher than you are actually going. They would be open to a lawsuit if they undersized the tires versus what the odometer read, though, because your promised warranty coverage is based on mileage.

 

[Froglips]

MPG based on first 10K miles

Have right at 10,000 on my 2WD SR5 now. Overall mpg (total miles/total gas) is 22.0 mpg with estimated 75 to 80% highway. Recent 3,600 mile road trip (Atlanta to Aspen via Nebraska and Denver) yielded 23.8 mpg overall. High was a remarkable 27.0 (65 on cruise) and a low of 21.8 (in a strong cross wind going across Kansas all calculated. I reset the mpg computer at the start of the trip and left it to run until back home. It amazed me that it agreed with the calculated 23.8 within a tenth of a mile per gallon.

 

[Fuzzylogic]

Have right at 10,000 on my 2WD SR5 now. Overall mpg (total miles/total gas) is 22.0 mpg with estimated 75 to 80% highway. Recent 3,600 mile road trip (Atlanta to Aspen via Nebraska and Denver) yielded 23.8 mpg overall. High was a remarkable 27.0 (65 on cruise) and a low of 21.8 (in a strong cross wind going across Kansas all calculated. I reset the mpg computer at the start of the trip and left it to run until back home. It amazed me that it agreed with the calculated 23.8 within a tenth of a mile per gallon.

Yes. It is actually pretty accurate. I also calculate at every take and have found the computer to be very close.

I drive a lot of highway miles as well. My average is in the 20s. I've never had a tank average below 19. But...I rarely drive a lot of stop light to stop light, in town routes.

I'm a happy guy. My Titan never got BETTER than 14.75 blended...I got "thank you" letter from OPEC.

EDIT. Error...I did have one tank average of 15.5 on a trip to the Florida Keys. My wife was driving. She is genetically incapable of exceeding 65 mph.

 

[Fuzzylogic]

Have right at 10,000 on my 2WD SR5 now. Overall mpg (total miles/total gas) is 22.0 mpg with estimated 75 to 80% highway. Recent 3,600 mile road trip (Atlanta to Aspen via Nebraska and Denver) yielded 23.8 mpg overall. High was a remarkable 27.0 (65 on cruise) and a low of 21.8 (in a strong cross wind going across Kansas all calculated. I reset the mpg computer at the start of the trip and left it to run until back home. It amazed me that it agreed with the calculated 23.8 within a tenth of a mile per gallon.

Yes. It is actually pretty accurate. I also calculate at every take and have found the computer to be very close.

I drive a lot of highway miles as well. My average is in the 20s. I've never had a tank average below 19. But...I rarely drive a lot of stop light to stop light, in town routes.

I'm a happy guy. My Titan never got BETTER than 14.75 blended...I got "thank you" letter from OPEC.

 

[wrong way ron]

18.1 city and hwy

 

[iDRiVaT4R]

Thought I'd update my stats after having my new tires for about a month now. I reset the mileage computer and it show's I'm averaging 14 mpg. Of course its not accurate since I'm running 285/70R17's but I don't think it's too far off.

My gas gauge never stops moving now unfortunately. Before it would stay in a spot for at least a little while, now it's always moving. kinda sucks but Oh Well!

Maybe it's due to the weather, it's been colder than usual the last few weeks in So-Cal. I know my 4Runner always seems to run best when the ambient temp outside is in the 80's-90's and lately it's been in the 60-70's.

 

[sandcrawler]

currently averaging ~18.0 @5k miles and almost entirely city driving. this is with the heavier E load range Duratracs (stock size) and a decidedly non-aerodynamic thule rack (not using a fairing currently).

i'm happy enough, but hope it will continue to improve. i didn't buy it for the fuel economy, but given that i gave up the 4G's V8 i would like to see a marked improvement nonetheless.

my update: nearly constant 18.3 mpg at 7000 miles, so it's climbed only slightly. figure a fairing will (still) help, but surely the extra oomph necessary to get the 44 lb. Duratracs (vs. the 39 lb. Dunlop stockers) rolling in stop-and-go driving is having an effect.

 

[tblackj]

Thought I'd update my stats after having my new tires for about a month now. I reset the mileage computer and it show's I'm averaging 14 mpg. Of course its not accurate since I'm running 285/70R17's but I don't think it's too far off.

My gas gauge never stops moving now unfortunately. Before it would stay in a spot for at least a little while, now it's always moving. kinda sucks but Oh Well!

Maybe it's due to the weather, it's been colder than usual the last few weeks in So-Cal. I know my 4Runner always seems to run best when the ambient temp outside is in the 80's-90's and lately it's been in the 60-70's.

I'm right there with you. I'm running the Gobi Rack and the 285 MTR's and I got a little under 16mpg on my last road trip. But the funny thing is, I get about 15mpg around town! Not much difference at all. The aerodynamics on the truck suck when the mods start.

 

[snow&surf]

The aerodynamics on the truck suck when the mods start.

This! Was averaging 18.4 combined prior to lift and tires, now 16.1 combined.

 

[iDRiVaT4R]

That sucks! Are you still on 17" diameter wheels?

I just did some math. Assuming you're on 8.5" radius wheels and that you've increased from a tire sidewall height of 7.44" to 7.854", the circumference of your wheel has changed by 2.6%, which means that instead of 14, you're actually getting 14.4 mpg. There's a big difference in the friction losses 'cause of the wider tire. Ouch! I feel your pain =(. Hope it was worth it!

Well, IMO my 4Runner looks better with the larger tires and the new wheels. So far its worth it. These mpg figures are pretty much city driving. Most of the time I'll arrive at my destination before the engine is even at operating temp. The last descent length drive I had was on the way to Glendale to pick up the new wheels and tires. I don't think I can really blame the rack much since It's mostly city driving I've been doing.

 

[simple06]

I was averaging 19 mpg city/highway and 21 mpg highway. I put on BFG KM2's and kept the stock size. I lost 2 mpg on both my averages.