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The last month or so has been a struggle to get good MPG. My tanks are still good but it was more work. It occurred to me that I hadn't checked my tire pressure for several months. Lo and behold my tires which I had set to 40 psi were now down to 32 psi :eek::eek::eek::eek::eek: Amazingly I still get 57+ tanks with underinflated tires however this just tells me that they would be 59-60 tanks if I was a bit more diligent.

I don’t think 32psi is under inflated, although I am running 40psi in my tires right now. What I don’t like is the floating feeling while driving on the highway. I’m going to lower it to 36psi to see if the ride on the highway is better, more stable and more to my preference of ride.

32psi checked while the tires are warm IS definiately underinflated and down right dangerous.

remeber you will lose 1 psi for every 10F drop in temperature. That makes it even more dangerous on cold mornings.

**** i got to get a jack since one of my tires air thingy is blocked by the plastic hub capp. this time i'm going to buy 4 air compressors so I can rock all four tires at once!

ahahahah oh boy what a PSI nerd i am.

Lol

:lol:

I drive a 05 chevy cobalt my potenza's g-009 i keep at 40psi. Its alittle rough but handles better i tried 32-35 an it feels to soft. I get 22+City/34+Hwy

I recently checked my tire pressure and found that it was around 47 psi (it had been filled originally to 55psi), so I filled it to 60psi. The reduction in rolling resistance was immediately evident and it looks like I'm on my way to a 70's mpg tank. The last few tanks had been pretty lousy (mid to high 60's ), no doubt due to the low tire pressure.

Bump for this thread because it was 34F this morning and I'm sure my tires are not at 40psi like I set them a month ago :)

Well, I checked and found that my tire pressure had lowered as well, so I filled them up with my compresser, and noticed my front right tire was unusually low. Then today, I looked at the parking lot and it looked half full. I took it to a tire place, and had it repaired; turns out there was a screw in it, and it was leaking slowly on top of that.

Got it repaired, and back on the road. Already up 3 MPGs on my tank average! (I had noticed I had dropped, and was having difficulty maintaining usual low end MPGs.)

Hi All:

___I performed my quarterly check of the pressures to the vehicles today. Ranger was down to 48.5 - 49.5 so I brought her back up to 55.0. Accord was down to 57.5 - 59 so she is back up to 62.5 and the MDX was down to just 41 - 42 so she is back up to 45 all around.

___Just a heads up as it is a bit colder now and at least in IL., it is one of the last remaining warm days left of the year …

___Good Luck

___Wayne

What are Honda Civic Hybrid owners have their tire psi set at?? I need to inflate my tires and I am not sure how high I want to go. Thanks:)

My HCH I tires go from 50 to 60 depending on how long it takes me to check them. I pump them up to 60 warm not sure what that would be cold.

I just checked my tires a couple of days ago and they were right on 60 psi for all 4 of them. It had been at least a month since I had checked them last. Oops!:o

I try for 50. Try to check every two weeks. Very reluctant to higher, but others go for 60?

I have been running 60 psi for ~5,000 miles with no ill effects on my current tires. I drove the car my son is driving("my temporary ride" in mileage logs) for well over 10,000 miles this way. The tires are Goodyear Assurance Comfortread's and are 185/65/15's. I ran them as high as 70 for a month or so but saw no real difference in FE so I brought them back down to 60. As has been stated before on cleanmpg, max psi is a personal decision that can really only be determined by you. Also, if you want to raise pressure, it could be helpful to raise the pressure gradually while you get used to it. My $.02.

Checked yesterday. Anticipated having to do some inflation, but the fronts were 51psi and the rears were 49psi. That's right where I left them. I was really surprised.

Wow. I check my air pressure at least once a month. At least. I do find my wife complains if they are a little on the hard side.
On a recent trip to Seattle, I thought my rental car handled mushy.
Goodyear eagles touring. Manufacturer recommended 44 psi. They had 30 in them.
I spotted a a tire inflation sticker in the door jam. It said inflate to 30 psi all around.
With the low profile side wall and considering Goodyear payed some engineers to come up with this psi, Ride, handling etc. Just to have some desk jockey somewhere decide he/she wants their rental cars to have this in the tires.
Somebody gonna get hurt.

Please be carefull on slick roads if your are inflating your tires higher that the maximum cold inflation pressures that is listed on the sidewall of the tire. Using high performance tires will also give you more traction in poor conditions.

Also, in cold weather on wet roads the rubber may not get warm enough to provide adequate traction for an emergency stop or maneuver. Please remember to keep safety in balance with your desire for maximum mpg! I Use a very large following distance usually about 10 seconds.

Car manufactures do not recommend using high tire pressures because it provides less traction in some conditions like winter driving. They have to put safety over minimum rolling resistance. Tires that could handle the high pressures and provide the necessary traction would have very soft rubber(like those temporary spares), wear out more quickly, and be more expensive.

I use maximum tire pressures in warmer weather but reduce it during the winter to about 5 psi above the sticker pressure. Lower pressure creates a larger contact patch with the road and allows more tire sipes (those molded cuts) to be in contact with the road and provide more traction. You don't really need those sipes (see racing slicks) on dry warm roads because the rubber is warmer and stickier.

I have a tire pressure page on my web site and cannot recommend using high pressures for lialbility reasons(read some people will crash and blame it on the higher than sticker pressure). Low rolling resistance can be safely obtained by using enery efficient tires that are designed for higner pressures (like those found on hybrids).

my sumitomo htr-200 are rated at 51psi. i run them at 50. the high pressure was one of the reasons i chose them. low rolling resistance and good grip were other factors. seems i am giving up about 8 mpg to get vastly better handling.

Hi Mpgmann:

___Being a new member, you will receive a fair bit of leeway wrt your commentary. You will also have to learn that most of what you just posted above is fictitious at best. Promoting your own HW sales site while adding inaccuracies here is not what I consider ideal so please be very, very careful. Learn your products as well as the ramifications if you want to sell to those that know what the facts are and I would highly recommend that you learn to use the search function and understand the facts before posting similar in the future.

___Good Luck

___Wayne

Gah, I'm checking mine tonight! It's been warmer recently so I'm probably OK but it's always worth checking. :cool:

I checked mine yesterday. I need to let a little air out as they were at 43 psi in the afternoon. I like mine at 40 in the morning (about 5 higher than the door sticker recommendation).

If we may posit that heat is the enemy of tires...

They will always flex (more or less) during driving, and thus heat up. But if a non-contact infrared thermometer is not available, the simplest way to measure heating is with your pressure gauge.

Set the tires when still cold, to your liking. Then go driving a good long distance and measure their pressures again. If they have increased by more than 10 or 15%, this indicates excessive heating. It will have been caused by initial underinflation, too much weight, excessive cornering or braking, or some combination.

On another day, initialize at a different cold psi and repeat the exercise. It is most likely that you will get less hot pressure increase by starting at a higher pressure. If you cannot get that hot pressure increase below 15% at any pressure equal to or less than the maximum sidewall inflation, this indicates that your tires are not adequate for your driving conditions.

In particular I am not advocating cold inflations above the sidewall number. I do suggest that the maximum attained 'hot pressures' are not constrained by the sidewall cold number. What you are trying to achieve is tire heating in use that is less than that causing a 15% pressure increase when hot.

This came from Jerry Jorgenson, and if someone is interested in additional info, I can ask him to provide a tire industry technical document.

DAS

I have ran Bridgestone Potenza RE92's at 60 psi for about 85,000 miles with no ill effects.
My wife's Toyota Solara convertible with Bridgestone Turanza EL42's have been at 45psi since the car had 4000 miles on it. It now has 28,000 miles.

Thanks for the info. I would not have posted my site if that was listed as not acceptable in the posting guidelines. I have tried to balance safety while passing on some basic ways people can increase their MPG just like you do. I did a lot of reasearch on tire pressures before I wrote my tire pressure page. I design parts for commercial jets and we go to extreme lengths to insure public safety. We examine every dangerous senario under every possible weather condition and design for it.

Auto engineers have to do the same. They do extensive vehicle safety testing. If only 5% of the time (on bad road conditions) their tire pressure recommentations could cause loss of control or an accident, then a large number of poeple could be hurt or killed. We need to be careful on poor road conditions.

Please point out where I can learn more about driving safely with high tire pressures. I am always open to learning something new.

Hi Mpgmann:

___You can start here: Driving Under Pressure. (http://www.officer.com/article/article.jsp?siteSection=19&id=27281)

___After that, look up the GY Tire study on wet and dry traction at various pressures. After that, look at any number of posts around the net on tire wear patterns of any number of Prius I’s RE92’s, HCH-I’s B381’s and Insight RE92 owners when not bringing up their pressures to a minimum of MAX sidewall. After that, look at the mileage numbers from people that have posted into this very thread. 80,000 from RE92s’ rated for < 30. How about some 80,000 mile rated Michelin MXV4 +’s at 78,000 w/ 7/32’s still left? After that, lower your tire pressures to door pressures and take a hard and fast corner out in the middle of an empty parking lot. Hear the screeching? Do the same at higher pressures and guess what, the car goes where you tell it to. Lastly, you really need to speak with the engineers that designed your tires to find out where burst actually occurs. It will shock you but the only way you are going to burst a tire nowadays if it was dry rotted, wear bars are showing, std, road debris or conditions takes them out, low pressures with high loads and/or heat or are grossly overloaded at any pressure and doubly so when under inflated.

___Good Luck

___Wayne

Good post - I really liked the link. Makes thing a lot clearer.

I'm at 45 psi. How high should I go?

I would not have posted my site if that was listed as not acceptable in the posting guidelines.

I think the reason Wayne removed the link to your site is because your guide on tire pressure is inaccurate and may mislead members here or at least confuse them with conflicting information. I know you worked hard on it and it isn't bad. I'm sure once you read the information Wayne linked to you can correct it and then we can allow a link to your site.

Wayne works very hard to educate people and wants to ensure that misinformation isn't perpetuated.

Hello all,

I just this past Month decided to see how much difference there would be in my ride quality if I dropped my Tire-Pressure to 35 Psi. So I did some weeks back and here is what I have found.

Remember this is just my "Personal-Opinion" and in no way am I telling anyone what to set their tire pressure on.

The ride now on my 2006 HCH II is Very-Smooth and I think it is also somewhat Quieter. The owners manual and in the door face says it should be on 32 Psi. I decided to go with 35 Psi and see how I liked it. I-Do A Lot infact. There is a lot of difference in the interstate ridges, bumps, difference in height of pavement ride quality over these surfaces.

So I think I will leave it where it is and enjoy the Smooth-Quieter more luxury ride quality of my HCH II.

I have driven the same car with tire pressure as high as 60 Psi and everything in between the now 35 Psi and the 60 Psi.

As always it is just a personal choice like many other decisions we make regarding our vehicles.

So I would say for "Maximum FE" you can go to 60 Psi and never worry about anything Bad happening. If on the other hand you want that nice smooth, quite luxury ride then go to as an Example 35 Psi for the HCH II.

Have a nice day all. :flag:

Terry (tiger)

Checked mine tonight and still at 46/44 from 2 months ago. (Granted it was much colder 2 months ago.) Still need to get in the habit of checking it more often just in case!

Between this and other threads I keep hearing mention of folks having to drive several miles to get air for their tires. I think it's worth mentioning that you can get your own small air compressor for less than the cost of a tank of fuel.

I have a little 12V DC unit made by Campbell Hausfeld that I paid $12 for at a Wal-Mart a little over a year ago. It's not the fastest tire filler I've seen but I have more time than money, and this little thing has paid for itself time and again not just in functionality but in convenience. I find I'm much more likely to be religious about my tire pressures if it's convenient to replace the missing air. ;)

Between this and other threads I keep hearing mention of folks having to drive several miles to get air for their tires. I think it's worth mentioning that you can get your own small air compressor for less than the cost of a tank of fuel.

I have a little 12V DC unit made by Campbell Hausfeld that I paid $12 for at a Wal-Mart a little over a year ago. It's not the fastest tire filler I've seen but I have more time than money, and this little thing has paid for itself time and again not just in functionality but in convenience. I find I'm much more likely to be religious about my tire pressures if it's convenient to replace the missing air. ;)

Good point. Those 12V units are convenient and portable. What I usually use is a bicycle pump (one that you brace by standing on and pump vertically) and it works just as well. No excuses. ;)

Does anyone know anything about the low pressure monitor on most cars?

I know on my Prius you can calibrate it to whatever pressure you want, but I don't know the delta below "calibrated normal" it can go before alerting.

Anyone know the delta before it alerts on Toyota?

So the way I figure it, If the delta is 10 PSI, and I want my tires at 46/44 PSI then I'll calibrate it at 51/49 (or when they are warm), drop it down (or let it cool) to 46/44 and it will flash the light if they ever get down to 41/39 or worse.

In any case, I'd suggest new car owners read the manual to figure out how to calibrate their sensor then set it as soon as you inflate.

11011011

I just got my tires rotated and pumped up yesterday. You should have seen the guy’s face when I told him I wanted them at 48psi. His eyebrows shot up, I swear I’ve never seen eyebrows go that high. He gave me that "are you sure you know what you’re doing" look and started lecturing me on how I could be damaging my tires to the point where the tread could separate and be catastrophic. I couldn’t help think of Scotty yelling “I cahn’t put anymore pressure on the warp engines, Keptin, they’re ready to blow!” I had to initial that they advised the max rating and I still wanted 48.

Later I look over at the genius sitting in my car and he’s staring hard at my dash and randomly punching buttons. O-M-G. Lucky I ran over there before he zeroed my trip A and B. He just wanted the odometer for my paperwork. So, a warning to everyone who takes their car in for service—make sure you’ve left the dash set to show the full odometer reading when you give them the key.

The tires were at 44 before so I feel a little difference in the ride now but I’d call it firm, not rough. I still like the way the car turns into curves and corners though.

Hi Tarabell:
Scotty: I cahn’t put anymore pressure on the warp engines, Keptin, they’re ready to blow!”

Later I look over at the genius sitting in my car and he’s staring hard at my dash and randomly punching buttons. O-M-G. Lucky I ran over there before he zeroed my trip A and B.
___You certainly do have a way of “cutting to the chase” with a story that is not only to the point but pertinent to the rest if us. And it usually places a smile on some of our faces in the process :D

___Good Luck

___Wayne

lol, tarabel :) Great analogy.

I think we have all seen that look. Last week when I brought my car in for maintenance the guy wrote on the check list tires 65psi!!! (three exclaimation marks included)

Dohh... 2 lbs low.... have to correct once the tires cool down.

11011011

I read that one before. Those guys in the truck are showing us just what can happen when a high CG vehicle takes a hard turn at speed with over inflated tires. Instead of the tires rolling over, the truck does. If the car makers could put higher MPG numbers on the window stickers by just adding air in the tires(without taking a safety hit), they would do it in a heartbeat.

And of course big heavy cars driven at the limit will handle much better with higher tire pressures. Also note that they only recommend using the maximum pressure that is listed on the sidewall. You have said before that the only thing that suffers with high tire pressures is braking distance. That is because part of the way a tire gets traction is by molding itself to the rocks and texture of the road surface to physically grip it. The smaller contact patch caused by high pressures will result in less grip on wet or dirty pavement. That’s not a problem with the way that you and I drive because we get off the gas so early and don’t need to brake much.

But my wife and kids don’t drive as carefully as I do (faster with less following distance) so I have to provide them with maximum traction for those panic stops on these wet Seattle roads! Their safety comes before maximum MPG. We know how to compensate for the mods that we have done. Most hypermilers won’t have any problems running 110 to 120% of the max sidewall pressure most of the time on good road surfaces. All I am trying to say is to be careful in low traction conditions, leave more following distance, and make sure anyone that drives your cars does the same.

There are so many other things that people can do that do not pose a safety problem under any conditions. Rolling resistance is only about 5% of the total energy losses in most cars. Don’t forget to also stress reducing engine pumping losses, improving combustion efficiency, reducing engine friction, transmission friction, driveline friction, reducing aerodynamic drag, reducing weight, proper maintenance, checking wheel alignment and brake drag, using a regular grade top tier gasoline, and minimizing trips taken from a cold start.

I would still use very high tire pressures for those record or personal best runs!

Good luck and break some more records! :bananapartyhat:

Hi Mpgmann:

___You still are not getting it. Traction increases and braking distance decrease under many more circumstances then you portray let alone the roll over discussion. The X-Crossers in Insight’s have very interesting lap data and “Seat of the pants” data wrt low pressures vs. the preferred high as well.

___Nobody is telling you what to do but you appear to be telling others what you think vs. what is actually known.

___Good Luck

___Wayne

When I first got my new Civic I went right to sidewall pressure which is 51PSI. I kept a good rotation and alignment schedule and at (only) 88,200 miles were replaced with the tread evenly wore across and almost touching the top of the wear bars.

My tires inflated that way still had plenty of grab except in the usual puddle situations and I take some pretty hard Right turns with a dead stick.

I had them replaced with the same type of Dunlop SP20FE and after leaving the dealership thought how smooth the new rubber feels. But after seeing a ~7MPG loss I thought to check the pressure. Sure enough they put 32PSI all around so I pumped them up. Now they're really noticeably hard. Life is good.
While my soft, pliable new tires aren't as efficient as my old, rock hard rubber tires they are doing just fine.

-Steve

MGPMann,

You are wrong. First, where is the center of gravity on a car vs a truck? Roll over isn't an issue. Second the only times traction is decresed is in snow and I suspect sand for the reasons you mention. Normal roads do not have a problem because the treads are soft enough to conform around small debris found in normal driving.

I totally agree with the views of many in this forum concerning the benefits of sporting a higher tire pressure. So much so that I've made an effort of installing a TPMS (Tire pressure monitoring system - Direct Type) on both my cars.

In fact, since I seem to spend a greater time at GreenHybrid (my apologies :o) , I kind of got another member there to install the exact same system on his HCH-II as well. Here's the thread:

http://www.greenhybrid.com/discuss/showthread.php?t=12286

The thing about this system is that it fully supports my paranoia concerning higher and steady tire pressures by allowing me to customize my alerts for lower pressure and temperature thresholds to values that I choose. Additionally this system is very easy to mount and very affordable. I and 06HCH2 be posting some pics of the system. :)

Anyhow, when I first installed the system on my HCH-II I had an experience very similar to Tarabell's. I took my OEM wheels to the Tire shop (GoodYear & Dunlop) to have the rubber removed from the rims (at that time I had my winter rims and tires on the car). The guys removed the tires "carefully" as they were scared on the rather large mirror finish area on the OEM rims and bagged them for me. I then picked them up, installed the TPMS sensors on each rim then I took them and the tires back to the tire shop. I instructed the technician that I wanted the tires set at 48 psi. He did not write that down but said OK (perhaps mindlessly).

Later when I picked up the wheels I noticed that the tire pressure was set at 34psi. I asked them why they did that when I had explicitly requested a higher pressure. The guys at the front counter including the manager promptly tried to correct me... that it is wrong to have it any higher. Their claim is that regardless of the max rating their policy is to pump no more than 35 psi... I kindly explained to them why I wanted the tire pressure higher and they all looked like a bunch of deer staring at the headlights.

In the end, they said it was the first time they ever heard such a thing, but they reluctantly pumped the tires to the requested pressure. Funny thing is that they actually kept an eye on the apprentice that was inflating them - perhaps wondering if the tires would blow up or something. :P

Cheers;

MSantos