I believe this is done to try to create a cushier ride with somewhat less road noise, raher than for mileage or performance reasons. While I have read that running overinflated tires leads to premature wear on the center of the tire, my original tires were absolutely even in terms of wear, which leads me to believe that the recommended level is actually slightly underinflated compared to what the tire could optimally handle.

If the levels of road noise and bumpiness of the ride don't bother you, I say run the pressure as high as the max sidewall rating on the tire. I ran my previous OEM tires at 44 all the time, and found that the car was more much responsive for cornering, and gave me better road feel. In addition, it dramatically lowered my rolling resistance (tested by coasting down known lengths of hills from a certain MPH and seeing how fast I could get up to). The only drawback as far as I'm concerned is extra road noise when driving over uneven roads. I'm actually thinking of adding some sound dampening materials to the car to counteract this.

Right now, I have Kumho 711 Summer Tires on the car on aftermarket 16" rims, and also have those pumped up to 44 (max rating). Since those tires are slightly wider and grippier than the older ones, I saw a much more dramatic difference in rolling resistance between 30 and 44psi. At 30, the extra resistance was very noticeable, but at 44, I'm achieving almost the same coasting distance as the stock LRR tires (that absolutely sucked in rain and around corners by comparison).

 

TheOcean,

You probably know this (but just in case), make sure when you deflated those tires, that it was COLD tire pressure you saw at 46 PSI, not HOT. You should check tire pressure after the car has not been driven (at all) for several hours. I check before leaving for work in the morning. Just be absolutely sure your tires are not under-inflated (it's blowout-due-to-overheating-dangerous).
Also, as someone else mentioned on this thread (and it's all over other threads ), the consensus is that higher tire pressure (up to a point, for sure) will result in somewhat better MPG.
Your 7- mile average trip is probably killing your MPG more than anything else. The car is barely warmed up (just like any other car would be, too), and you're done. I bet previous autos taking this same 7-mile average trip fell considerably short of the EPA MPG ratings. The Civic Hybrid will be no different. Console yourself in the knowledge that you should be getting much better MPG than if in one of those other vehicles.

My wife used to drive our Jag on a short <10-mile trip to work. She averaged about 14 MPG . Now, I drive it on a 35+ mile trip to work. I average 19-20 MPG. Some of that is due to more highway-drive-time for me, but much of it is due to the fact that the warm-up time is such a large percentage of her short trip, and not so on mine.

 

I have found governerment (NHTSA) studies that back this claim, but they only go to 35 PSI. So at least up to that point, everything but ride comfort gets better as PSI increases, wet/dry traction, wear, hydroplaning, so you can confidently go up to 35 PSI (and probably 40ish) based on solid data.

My belief is the warning about uneven tread wear for "overinflated" tires dates to the days before front wheel drive cars were popular. Since FWD chews the sides like crazy, the old concerns about premature wearing in the center with the sides untouched just don't make sense, and enough people have tried it in this group to confirm that it just doesn't happen.

The NHTSA is also advocating tire pressure monitoring systems (TPMS), I think in part because manufacturers play games with low PSI recommendations. According to them, just a few PSI below 32 (mid to upper 20's) and you start to get into the range where catastrophic tire failure occurs due to underinflation. I always think of the Goodyear fiasco when the recommended tire pressure was so low that if you didn't fill your tires weekly they went KABOOM!

Much safer to inflate to around 40ish, and if you forget to check your tires until they drop to 35 (a few months), much safer than if they drop down to a life threatening 28 or so from the measly recommendation of 32.

 

I picked up my 06 HCH II on 4/10 afternoon and today I just filled it up for the second time (I have over 850 miles on it already - my daily commute is about 160 miles). My first tank averaged a calculated 42 mpg vs. an indicated 41 mpg. My second tank averaged a calculated 43.5 mpg vs. an indicated 43 mpg.

My previous car was a 4x4 SUV which I averaged between 18-19 mpg.

The first 30 miles of my commute is on the turnpike (between 75 - 80 mph), the next 30 is on a highway (between 70-75 mph) and the last 20 is local (between 35-50 mph with stop lights/signs). My travel time to work is about 1 hr 25 minutes.

I don't take the turnpike home so the last 30 miles of my return trip is local (between 45-55 mph) to save the toll as well as avoid some traffic - my return trip time is about 1hr 40 minutes.

I was actually impressed with my gas mileage as I was concerned about my highway speeds killing the mileage. I am sure I could get better gas mileage by slowing down to speed limit (turnpike speed limit is 65, the highway speed limit is 55). For now, the decrease in mileage is worth the 20% reduction in my travel time. My avg mpg does climb when I drive the 20 miles in local traffic.

I have found that my avg mpg drops when I drive to work as the road is usually up a grade/hill. On my return trip, when I don't take the turnpike, it comes back to where I started in the morning. If I take the turnpike home, I would lose 0.5 mpg off of my average.

My first tank of gas was at the standard tire pressure (32 psi). My second tank of gas was with the tires at 40 psi - although I may lower it slightly as I have noticed an increased amount of road/tire noise. Of course regular has just crossed $2.75/gallons in PA so I may just deal with the noise to get better gas mileage.

 

Must be fun to watch your gas costs drop in half, especially when you drive 2 hours a day, that is a lot of cash. :-)

 

try setting CC at 55 mph and watch that FE climb.

 

Right - unfortunately some of the savings have been taken back from the gas price rise......

My biggest concern now is how it handles the snow...... but I guess that's why they make snow tires.....

 

Yeah, setting CC aroung 55-57 would improve the milage as said,i get around 49 and 52 with CC set between 55-57 for a commute of 60 miles daily and 45 mins of drive on highway and downtown.

 

Actually I think of increased gas prices as increasing savings over what I would be getting, the higher they go the happier I am I got a hybrid. It is real money that you aren't spending. And gas prices have nowhere to go but up these days.

The UK is creeping up on $6/gallon (if I did the pound and liter conversions right).

 

Well I started using Cruise control yesterday, and the MPG has definitely improved so far. It's definitely more effecient than what I can achieve with my own footwork! I'll keep you guys updated on my progress within a week!