2008 T4R Limited V8 4x4 - How much difference in gas mileage from 5w30 to 5w20?

[OrdnanceMarine]

I always was under the impression that if you let air out of the tires you get better traction? I'm actually pretty sure of this.

Less air in the tire = more surface area contacting the ground.

True with regard to sand/rock/dirt/dry pavement, etc. but not true when you're talking about water or ice. With water (or ice to a lesser degree) you're looking for less surface area which creates more pressure per square inch to "sink" you through the material that's slick.

 

[webby]

True with regard to sand/rock/dirt/dry pavement, etc. but not true when you're talking about water or ice. With water (or ice to a lesser degree) you're looking for less surface area which creates more pressure per square inch to "sink" you through the material that's slick.

Check out this amazing video of a flash flood in Australia just a few days ago for a little levity amongst all the tragedy. Obviously the guy getting in his big Land Cruiser or whatever it was, just in time to save it from the flood, didn't believe the principle you state. He used valuable time, while shielding himself from the rain with a bumbershoot, LOL (mustn't get damp while saving your ride!) to let some air out of two of the tires before driving his rig to safety. The action with him starts about 1:10 into the youtube video.

YouTube - Toowoomba Flood 2011.01.10

 

[OrdnanceMarine]

Put 36-38lbs of pressue in the tires if there's a P preceeding the tire size. If LT, 40-45psi.

I'm a little surprised to see such high pressure recommendations from the members here. Factory recommendation is 32, correct? (at least for my SR5 with 16" rims). When I bought my 4Runner back in November I made a wrong turn getting back to the freeway and spent a few miles getting acquainted with the alleys and rough roads around the 215 in Riverside where everything is under construction and they have removed many of the freeway on-ramps. As I drove over speed bumps and through ditches I began to think to myself that this 4Runner drives a whole lot more harshly than another similar one that I've spend hundreds of miles in. Those tires were bouncing off everything! Keep in mind that I daily drive a Civic Si on 215 45 17 Maximum Performance Summer tires at temps below freezing and inflated 10-15% over the 32 PSI Honda recommendation and have driven lowered cars with shocks that dampen well in excess of 100% above OEM and springs with rebound rates quite a bit higher than stock.

The next morning I checked the tire pressure and it was 40 PSI! No wonder it rode so harshly! I had 20% more air than Toyota recommended! Those of you recommending 45 PSI, can you count the grains of sand as you drive over them? I dropped the tires to 35 PSI and the ride is much more tolerable.

If you dramatically over-inflate tires (40 PSI meets this definition unless you're towing a heavy trailer or cruising the wide oval at speeds the 4Runner can't achieve) then you start to lose surface area and you will negatively affect braking distances while not improving mileage appreciably. In other words, you're screwing yourself.

You're probably fine going 10% above Toyota's recommendation and gaining some efficiency and improved turn-in without hurting braking too much but I wouldn't go above that. If you're trying to wring 0.2 MPG extra out of your 4Runner then you bought the wrong vehicle. If that kind of fuel savings really matters then you ought to consider selling the 4Runner and buying a well used manual transmission Civic/Corolla, etc., get 40+ MPG and you'll have enough money left over to put 100,000 miles worth of gas in it before you even have to spend an additional dollar on fuel (100,000 miles @ 40 MPG is 2500 gallons @ $3/gal is $7500). Oh yeah, you could drive 100 MPH and still get better MPG than the 4Runner at 65 MPH.

If you're just trying to get reasonable fuel economy out of your 4Runner then the way you drive is absolutely, positively the #1 way to improve fuel economy and there are some good suggestions in some of the posts above. Tire pressure won't matter more than ~3-5% unless you start running 25%+ below Toyota's recommendations at which point handling will seriously start to suffer and you'll be sending your tires to an early death if you are spending time at highway speeds/heavy loads.

 

[OrdnanceMarine]

Check out this amazing video of a flash flood in Australia just a few days ago for a little levity amongst all the tragedy. Obviously the guy getting in his big Land Cruiser or whatever it was, just in time to save it from the flood, didn't believe the principle you state. He used valuable time, while shielding himself from the rain with a bumbershoot, LOL (mustn't get damp while saving your ride!) to let some air out of two of the tires before driving his rig to safety. The action with him starts about 1:10 into the youtube video.

YouTube - Toowoomba Flood 2011.01.10

I think he was locking the front hubs so he could engage 4WD and drive away. I notided the snorkel on his rig so I'm going to guess he's "been there, done that" in that vehicle, but I could be wrong.

 

[webby]

I think he was locking the front hubs so he could engage 4WD and drive away. I notided the snorkel on his rig so I'm going to guess he's "been there, done that" in that vehicle, but I could be wrong.

OK, you may be right. If you listen to the audio, the people filming it said more than once that he was taking some air out of his tires, so I assumed since they were there, that they knew what they were talking about.

 

[bigwebb83]

I'm not trying to turn my 4runner into a civic. I can afford it just fine. I do care about the mileage though. Especially when I read about members on here getting 20+mpg with mostly highway driving. I think my problem is a combination of a few things. The temp has been single digits since i bought the vehicle and regardless of what some may think letting air out of the tires improves traction (you don't just magically sink through the snow all the way to the pavement) and i thinkn the tires will be under inflated when i check. I also plan on the air filter, synthetic oil and synthetic diff and transfer case fluids. I think all of this plus normallizing temps (especially as temps warm up in March) will bring me up 2-3 mpg. We shall see though.

 

[TheSentinel]

I came across this wiki article. Its interesting that the BFG Rugged Trails did so well, figures why Toyota likes putting them on some of their trucks to give them better MPG numbers.
Low-rolling resistance tires - Wikipedia, the free encyclopedia

 

[JB.]

Originally Posted by JB.
Put 36-38lbs of pressue in the tires if there's a P preceeding the tire size. If LT, 40-45psi

I'm a little surprised to see such high pressure recommendations from the members here. Factory recommendation is 32, correct?

Correct.

It was a quick recommendation for a poster who was, unduly imo, concerned about mileage though I don't think there's anything wrong with 36-38psi in a passenger tire if someone prefers it, for whatever reason. The 40-45 recommendation was for an LT and, again, for said poster. Technically, LTs require 10-15lbs more pressure to retain the same load carrying capacity as the OEM passenger tires. It's debatable how strictly that needs to be followed but that fact, combined with the poster being concerned with mileage, made it a fitting sub-recommendation, imo -- my larger point about mileage being similar to the one in your post.

 

[OrdnanceMarine]

I'm not trying to turn my 4runner into a civic. I can afford it just fine. I do care about the mileage though. Especially when I read about members on here getting 20+mpg with mostly highway driving. I think my problem is a combination of a few things. The temp has been single digits since i bought the vehicle and regardless of what some may think letting air out of the tires improves traction (you don't just magically sink through the snow all the way to the pavement) and i thinkn the tires will be under inflated when i check. I also plan on the air filter, synthetic oil and synthetic diff and transfer case fluids. I think all of this plus normallizing temps (especially as temps warm up in March) will bring me up 2-3 mpg. We shall see though.

My reference was to those that advocate 40+ PSI in order to get a fraction of a MPG better results. Crazy high tire pressure that sacrifices braking performance is the kind of talk I see on Prius and Civic Hybrid sites, not what I'd expect on a 4Runner forum. Trust me, I know many of the fuel saving tricks. In my Si I can break 40 MPG on the highway keeping the speed limit, not drafting and keeping the engine running (in other words, nothing unsafe) in a car that's EPA rated 29 MPG HWY so I've figured out what does and what doesn't work and what does and doesn't matter.

I'm willing to bet that single digit temps is costing you a few MPG. 1-2 MPG if you're only doing 2 cold starts per day and going at least 15 miles each way. More if you are doing short trips and have more cold starts. Go ahead and change your fluids if they are due to be changed (DYODD for reasonable change intervals) but changing them for fuel savings alone will never result in enough of a savings to cover the cost of changing the fluids. I'm going to be changing mine because I want to be sure of the condition of what's in there since I just bought it used and the cost doesn't bother me. Changing your air filter to a K&N, etc. won't affect MPG one bit unless your current filter is seriously clogged.

One more thing comes to mind. Are you running the AC with the defroster? Shutting that off is worth about .2 gallons per hour which doesn't make a huge difference if you are screaming down the highway at 70 MPH but does make a good bit of difference if you are driving in the city.

 

[OrdnanceMarine]

Correct.

It was a quick recommendation for a poster who was, unduly imo, concerned about mileage though I don't think there's anything wrong with 36-38psi in a passenger tire if someone prefers it, for whatever reason. The 40-45 recommendation was for an LT and, again, for said poster. Technically, LTs require 10-15lbs more pressure to retain the same load carrying capacity as the OEM passenger tires. It's debatable how strictly that needs to be followed but that fact, combined with the poster being concerned with mileage, made it a fitting sub-recommendation, imo -- my larger point about mileage being similar to the one in your post.

Got ya. I wasn't aware that a LT tire would require more air to carry the same load. I always thought it was a function of how much air the tire contained and that LTs got a higher load rating from their ability to safely contain more air because of their stronger casings.

 

[JB.]

I always thought it was a function of how much air the tire contained and that LTs got a higher load rating from their ability to safely contain more air because of their stronger casings.

Both true but not linear across the two tire types.

 

[OrdnanceMarine]

Both true but not linear across the two tire types.

Definitely not linear, just a generalization. Sidewall support has quite an effect.

 

[JB.]

Definitely not linear, just a generalization. Sidewall support has quite an effect.

Linear was perhaps a bad choice of term. What I meant was LT doesn't just pick up in load capacity where P leaves off. It's at a pressure/load disadvantage that it only overcomes by handling much more pressure.

 

[simple]

:iagree:

I changed from 5w30 to 5w20 and have seen no noticeable difference. I have stuck with it since only because the TSB said I could.

Are you running it in your 04 too? The TSB only covers 06 and up I think, but I can't imagine there being a real difference in the 03-05 v6 and the 06-09.

 

[bigwebb83]

Go ahead and change your fluids if they are due to be changed (DYODD for reasonable change intervals) but changing them for fuel savings alone will never result in enough of a savings to cover the cost of changing the fluids. I'm going to be changing mine because I want to be sure of the condition of what's in there since I just bought it used and the cost doesn't bother me.

Yeah I'm not going to spend any money to get better gas mileage. I think people are taking this the wrong way. I didn't buy a V8 4runner and then say "oh my god I'm not getting 30mpg!!! Should I buy a turbonator?" All I'm saying is that I want to be able to get respectable fuel mileage on par with what some of the other members on here are getting with conservative driving habbits. I want to change everything out to synthetics because for me it just gives me piece of mind, and as someone in another thread stated, it gives you a warm fuzzy feeling inside to treat your vehicle to the best.

Another reason is I want to be able to accurately tell how much mpg I'm going to be losing (if any) switching from the g35 sedan to the 4runner. When I first bought that car I did the same thing. I wanted to see what was the absolute best mileage I could get out of it and then once that was established I stopped even calculating. Now I want to do the same for this vehicle for comparison purposes. My gut feeling is that I'll probably use about 10% more fuel but that will be offset by being able to use regular gas as opposed to premium.

 

[M1911]

Could I see an 8-10% improvement by switching?

No. The difference will be too small to notice.

 

[bigwebb83]

do you guys think I would lose mileage if I went with a 1" front leveling kit and eventually some 265/65/18's?

 

[Koz]

Got ya. I wasn't aware that a LT tire would require more air to carry the same load. I always thought it was a function of how much air the tire contained and that LTs got a higher load rating from their ability to safely contain more air because of their stronger casings.

LT tires are rated for up to 80 psi and 40 psi in them is not enough pressure. First off, the only reason to run LT is to tow or carrying weight. I have done a lot testing on tire pressure and I can tell you if you are towing or carrying weight you need to run near max pressure. The OEM (passenger) tires are rated for 44 to 51 psi and there is no reason you can not run 40 psi on a 4500+ lbs vehicle without any problems with wear. As far as ride comfort, that is subjective. If it feels harsh you can lower the pressure. I've found 38 to 40 psi to be the ideal pressure for a 4500+ lbs vehicle. I'm running 40 psi on my GX (5300 lbs) with OEM tires rated at 51 max. The ride is perfect. If I tow with these tires I will pump them up to max.

Koz

 

[M1911]

do you guys think I would lose mileage if I went with a 1" front leveling kit and eventually some 265/65/18's?

The higher you raise the truck the more air goes underneath and the worse your mileage will be.

 

[webby]

LT tires are rated for up to 80 psi and 40 psi in them is not enough pressure. First off, the only reason to run LT is to tow or carrying weight. I have done a lot testing on tire pressure and I can tell you if you are towing or carrying weight you need to run near max pressure. The OEM (passenger) tires are rated for 44 to 51 psi and there is no reason you can not run 40 psi on a 4500+ lbs vehicle without any problems with wear. As far as ride comfort, that is subjective. If it feels harsh you can lower the pressure. I've found 38 to 40 psi to be the ideal pressure for a 4500+ lbs vehicle. I'm running 40 psi on my GX (5300 lbs) with OEM tires rated at 51 max. The ride is perfect. If I tow with these tires I will pump them up to max.

Koz

My front end alignment shop, which has been around forever and has the best reputation in the area, recommended I run 38-44 lbs. in the tires in my 4Runner. Yet the car manufacturers and dealers, and the tire shops that sell and install tires, generally all push 30-32 lbs., and sometimes less than that. I just got a set of new Michelin Cross Terrains at Costco, and of course, they put them at 32 lbs, but I will probably push them up to 38 lbs or more and experiment with the ride and handling before I settle on a pressure that I like.