[qwassy111]

Without further comment on what the "right" pressure is? one of the nice things about tire pressure is you can try out the different pressures with a 10 minute adjustment that's free, and change back any time you like. So, if you run one pressure and have never tried another, I suggest you give it a try, look at the profile, do the water or chalk test if you want to get detailed, and then see how it handles. Kind of fun to play around a bit.

will likely go up to 35 all the way around myself. even on 16's

 

[MWeed]

Just look at your tires when they need to be replaced. Is the center of the tread worn out/way thinner and the sides thicker/pretty good? You have too much pressure. Are they just the opposite? Too little pressure. If they wear evenly across the whole tread, you're running the right pressure.

 

[GreenD]

OK, every thread needs a guinea pig, so I ran a test today. I don't quite believe the results.

I'm running Goodyear Fortera Triple Treds in 275/60R17 size. I've run 35 psi all around since new. The sidewall says 44 psi max pressure.

I was on my usual upstate NY trip the last 2 days. 200 miles each way, same route each way. 150 miles are at 52-62 mph so perfect for optimum mpg, the other 50 miles are highway at 72-74 mph. There was a bit of around town mixed in.

I reset my console when I left my house, and got 13.8 mpg on the way out. This is about what I've gotten this winter on a trip like this, maybe 14.3 max.

I was waiting to meet with a guy today so I pumped my tires up to 40 psi and reset the console, with the entire return trip at the higher pressure. I just got home and the console read 16.2 mpg.

My common sense tells me that 5 psi couldn't have given me 2.4 mpg more, a 17% gain. I'm just reporting the numbers as I saw them, and this was about as even a test as you could have, same trip in each direction. I'll check a few tanks of gas by the numbers and let you guys know what I'm getting now, and I'll have some more highway driving in the next week to test.

The ride was great on the highway and good secondary roads. Its bouncy and hard on bad local roads, with some wheel hop that tells me I probably ought to put some new shocks on. All in all I'd prefer to run a few psi lower but if I keep getting the mileage gain I'll stay with the 40 psi. That's the story, like I said in my prior post its fun to play around with, made the trip go by a bit quicker.

 

[IndyDurango]

Reverse your PSI direction and check again. Run the higher level THERE and the lower lever BACK as opposed to the first test. That eliminates up hill/down hill variances.

All in all? you WILL have better mileage at 40 vs 30 anyways.

IndyDurango

 

[Silver Ghost]

GreenD - good test, but I'm not sure it's 100% valid.
We make periodic runs from Albany area to Rochester area and return the same day. We always see better mileage on the return (West to East) than we do on the trip out. Typically 14 out, 16 home. Ditto when we were visiting our daughter in Oneonta - always significantly better on the West to East trip. The prevailing west to east winds have much more of an affect than you'd imagine. Although your trip involves traversing the mountains in both VT and NH, I imagine you're seeing some of the same effect.
I'd agree with Indy - if you can, run the same test, but reverse the pressures. You may still see better mileage on the way home, even with lower pressure, but it may not be as dramatic.

Joe

 

[Connman]

I run the max on the sidewall as well. (didn't want midnite to think he was "wrong" for doing so)
At this point I couldn't care less about the ride. Anyone knows higher pressure = less friction = better gas mileage.
I've never had any uneven wear issues or blowouts.

Sure, running that high for some of you who have offroad tires would be stupid, but a truck that's 100% street, if you can live with the ride, there's nothing wrong with it.

 

[GreenD]

Joe, I'll do exactly that, run the same test in the opposite direction. I may make the trip next week, or in 2 weeks at the latest. I know what you mean about wind on the NY Thruway, I used to head out to Rochester/Batavia and then up to Ontario quite a bit. The surprising thing for me was seeing the over 16 mpg, I've never seen that since I've had this D, so no matter what I'm seeing some solid gains.

I'll let you guys know the results.

 

[tomk]

Sure, running that high for some of you who have offroad tires would be stupid, but a truck that's 100% street, if you can live with the ride, there's nothing wrong with it.

I found on my '99 that running with high tire pressures made the wheels hop on rough surfaces (like highway expansion joints) (even with aftermarket shocks), and this caused the ABS to be over-agressive and seriously hurt braking?

but YMMV?

the '03 was much less prone to this due to the very different braking setup?

 

[GreenD]

OK, every thread needs a guinea pig, so I ran a test today. I don't quite believe the results.

I'm running Goodyear Fortera Triple Treds in 275/60R17 size. I've run 35 psi all around since new. The sidewall says 44 psi max pressure.

I was on my usual upstate NY trip the last 2 days. 200 miles each way, same route each way. 150 miles are at 52-62 mph so perfect for optimum mpg, the other 50 miles are highway at 72-74 mph. There was a bit of around town mixed in.

I reset my console when I left my house, and got 13.8 mpg on the way out. This is about what I've gotten this winter on a trip like this, maybe 14.3 max.

I was waiting to meet with a guy today so I pumped my tires up to 40 psi and reset the console, with the entire return trip at the higher pressure. I just got home and the console read 16.2 mpg.

My common sense tells me that 5 psi couldn't have given me 2.4 mpg more, a 17% gain. I'm just reporting the numbers as I saw them, and this was about as even a test as you could have, same trip in each direction. I'll check a few tanks of gas by the numbers and let you guys know what I'm getting now, and I'll have some more highway driving in the next week to test.

The ride was great on the highway and good secondary roads. Its bouncy and hard on bad local roads, with some wheel hop that tells me I probably ought to put some new shocks on. All in all I'd prefer to run a few psi lower but if I keep getting the mileage gain I'll stay with the 40 psi. That's the story, like I said in my prior post its fun to play around with, made the trip go by a bit quicker.

I finally did the NY trip again, same as usual. I left the tires at 40 psi both ways, and got 15.8 mpg on the way out to NY, 16.8 on the way back. So, here's the summary:

NH to NY - 13.8 at 35 psi, 15.8 at 40 psi
NY to NH - 16.2 at 40 psi, 16.8 at 40 psi

I don't know how accurate all this was, the numbers are all off the console. I'm sold that the 5 psi increase gives me around a 2 mpg gain until proven otherwise.

 

[Silver Ghost]

Good test. Glad you did the same route at higher pressure to verify.
I don't know if I'd go much higher than 40. Fuel econpmy will start to level out and the D will be in a more unstable state.
I wouldn't want to trade safety for fuel economy regardless of prices (rant against the teeny cars).

Joe

 

[GreenD]

I agree Joe, 40 psi is the most I'll go. I do notice the ride difference at the higher pressure. I don't mind the extra bounce, in fact now that I've run the higher pressure for a month I barely notice it, but I'd like to get rid of the wheel hop, shocks should do that.

Like I said in my earlier post, this is a near-ideal trip for mpg, lots of driving at 50-60 mph. Still, I never thought I'd get 16 mpg on any trip so I'm happy seeing these results. I tracked 5 tanks by the numbers since the higher tire pressure and got 1374 miles for 94.8 gal = 14.5 mpg in mixed driving, lots of around town, lots of 70 mph highway. So, overall I'm maybe 1 mpg higher than I was earlier in the winter.

 

[IndyDurango]

Nice results, thanks for sharing. I always believed that the higher PSI improved MPG.

I too run 40 all the way around.

IndyDurango

 

[xbxjunkie]

x2

I run 40# all the way around cold.

IndyDurango

 

[FSTDANGO3]

Remember 40 psi cold yields about 44 hot
Just an FYI
Steve
DOC Pres