Just did a 275mi one way trip this wknd, 98% all fwy, mostly flat, one mountain pass....midnight run so no traffic, 75mph average speed. Yakima rocket box on top, two surfboards, prolly couple hundred lbs of camping gear and another cpl hundred pounds of dog and gf (combined NOT each, lol). 255/85 AT's, no lift, stock gears. And, truck was just tuned up, and I mean everything, including new 02 sensors, etc. Only got 15.6mpg!

So...I'm a bit surprised b/c a year ago I did a similar trip (about 3,000mi total vs. the 550this wknd) with the only difference being that there was nothing on the roof, no gf in the truck and 265/75 tires and managed to get 18.6mpg-19.2!

Does that seem right? A 3mpg diff b/c of tire size and no cargo on the roof??

And, are either of these figures about average compared to you guys with similar set ups? Whats your experience?

I was thinking of going to 285/75 but now am affraid it will drop the mpg's even more! Input on this?? Thanks

 

100% yes, those things affected it that much....I would have expected even worse than what you got.


Roof drag + 75mpg + tall tires = 15mpg every day of the week.

If you go to 285's, you'll lose probably 1 more mpg average combined driving.

Little note: if you would have only gone 65mpg on the freeway, you'd have helped your cause ALOT. I use a Scangauge II, and I've found that even with 265/75s and everthing else stock, average speed affects mpg a ton. If I cruise 20 miles at 50mph....I get 22.5mpg. Same road, same trip at 70mph results in 18.5mpg. Those 55mph speed limits back in the 70's to save gas actually had merit.....lol

 

Wow, good info there...thanks.

 

oh how i'm glad my 4runner will be slow...lol doesn't bother me to go 65

 

with that Parachute Air Brake set up you had on the roof I am surprised that you got that high of mileage, consider yourself lucky

 

Lol, c'mon...its not like I had boards standing straight up or anything....it all looks quite aerodynamic, well...more so then the brick shape of the truck itself at least!

 

you extended the brick shape, it is gonna impact the mileage.
The mileage on my Tahoe gets impacted dramatically if I use my Yakima pod.
simple aerodynamics.

as far as tires impacting your mileage, it will, but also take into account that your odometer is now off due to the change in rolling diameter. Figure your actual odometer now with a GPS.

 

oh ya, didn't think about the odometer....i do use gps though for speedo (which is now 2-3mi off), the 275 distance was from google maps. I literally have a gas station by my house then get on I-5 and drive straight to my camping spot...coast in on fumes more like it, and park

What's sad is that my buddy's full size diesel can do the same milage.

 

I know the feeling

One reason I am looking for a new(used) tow rig to replace my Tahoe. Too small of tank and the 6-8 MPG towing my trailer last week. Probably gonna end up with a 2002-2003 Chevy or Ford one ton...

 

285/75s and 255/85s aren't a big difference in gas milage, if anything the 255s get worse mpgs because they're taller than the 285s. Your mileage is about 17 or 18 mpgs taking into account your speedometer is off (which is about average). How are you runing 255s and no lift? You must rub on cracks in the road!

 

1" BL and pounding the hell outta the pinch welds solved all my rubbing issues, not even at full lock

 

Lucky you. I get 11.9mpg in town and 14.2mpg on the highway with my 3.4 swapped 2nd gen auto 4Runner. And thats with nothing on the roof and no one else onboard.

 

What?! On what tires and gears?

 

That's cool! Low COG and good ground clearance is great for the trails!

 

I dont know what the gears are but the tires are 265/70 R15's.
Gets 190 miles to a tank.

 

I would do an induction cleaning if I were you. I went from averaging 10-11 mpgs back up to 16-18 mpgs after a MotorVac service. Here's a write up I did:
http://www.toyota-4runner.org/3rd-ge...hopefully.html

It's been several months now and I'm still getting 16 combined and 18+ on the freeway.

 

your speed is probably the biggest factor. optimum speed for most gas engines is 50-60 mph. my 98 auto 4runner gets 20-22 mpg on highway at 60-65 mph with stock tires/gears and a moderate load.

 

Yeah, I drive everywhere at 70 - 75mph. But still, 14 on the highway? Retarded.

 

Brian, I do have the 8" LC wheels so maybe thats why I don't rub? Don't really do many trails...beach mostly. I'd like to get a lift but the $ seems to always go to bills.

20-22 to a gallon? Wow....nice. You must drive like my dad!

And ya, 14 would be unacceptable to me...oh wait...i'm like 1mpg off of that...hmm...

 

I think you would rub if you played in some rock gardens. I still rub here and there even with all the lift I have, but only when it compresses hard at full lock.