I'm running 32 psi (cold) all the way around and have averaged a bit over 28mph overall over the past 800 miles. I was thinking of pumping the tires up to 40 or so and seeing what that does to mileage. So...what are y'all running?

Poor tradeoff, tires for gas. Also can a safety issue on several grounds (see Ford Explorer rollovers for example). Do not exceed the tire pressure max listed on the tire. What will work is to purchase the low rolling resistance tires coming on the market. These tires can be hard compounds so you will loose some traction in dry conditions, lots in wet conditions, and all in snow and ice conditions. Having lived 10 years in DC you really don't get any real snow or ice so that is not a problem.

With all of the legal out of the way, it is important to keep the tp up to spec for your vehicle. The gains of increasing tp are small but the losses for low pressure are great. Diminishing returns problem. Running the smallest tallest tire (real retro look) you can find will help but probably more from tire dia then anything else. You will lose ride and handling somewhat.

I think mine are at 35 cold and when hot can get up to 38. This is how I got them from the dealer and haven't changed a thing on them yet. The TPM's haven't yelled at me either, do i'm just going with it being correct.

I checked my tire pressure one day when I came out from work and the tires sitting toward the sun was 2# more in pressure. My wifes uncle told us he replaced his air w/ nitrogen and it made a huge difference, so I contimplating changing also. I know from being around racing it makes a difference.

I have the 17" hi polished Alum that came w/car and the recom. pressure is 35 cold.

i thought i had read the nitrogen really doesn't do much at all. Could have been wrong as well, but i think it's pretty much in the air (ha ha, sorry). we should call myth busters on it.

nitrogen just doesn't leak out as fast as reg air which is about 78% nitrogen anyways. Just check your tires on a regular intervals and you'll be OK

Nitrogen doesn't expand as the temp rises like air does. Never heard that is leaks out slower.......nothing should leak out unless there's a hole. But, calling Mythbusters is not a bad idea.

I run at 40 because I have whitewalls that last longer that way.

Running at 42 cold - makes the road noise a bit louder but maximizes my mileage.

I've been running 44 in mine. Yes the ride is rough, but the pay-off is worth it on the gas end. The pressure branded on a tire sidewall is a recommended max pressure. For the best tire life you should always go by what is on the vehicle door placard. The higher the pressure, the least amount of rolling resistance but rougher ride and rapid tire wear while increasing MPG. Lower pressure is a much softer ride with more rolling resistance, thus lowering your MPG. Too low pressure causes massive heat build up in the tire carcass resulting in catastrophic tire failure (Firestone/ Ford fiasco).

Nitrogen doesn't expand as the temp rises like air does. ...... clipped.

Oh, yes is does! :roll:

Nitrogen doesn't expand as the temp rises like air does. Never heard that is leaks out slower.......nothing should leak out unless there's a hole. But, calling Mythbusters is not a bad idea.

Read this in a nice soothing calm voice.

ALL GASSES EXPAND WHEN HEATED. EMPHASIS ON "ALL"
(PV=NRT 22.4 LITERS PER MOLE AT STP can't change T with out changing P in a closed system)



LIQUIDS EXPAND HUGE! WHEN THERE IS A CHANGE OF STATE INTO GAS.
(TOSS A LIQUID CO2 CARTRIDGE INTO A HOT FIRE)
(or a mole of water weighs 18 grams wich is about 18ml= 0.018liters....heat it up until it turns into a gas voila volume changes by 22.4/.018 haha big number)


SMALLER MOLECULES ESCAPE ANYTHING FASTER THAN LARGE ONES.
(HYDROGEN CAN PASS THROUGH THE DENSEST METALS LIKE A GOLF BALL THROUGH A SOCCER NET, which is one of many reasons hydrogen powered cars is just a dream for now)

No need to calm myth busters. Just ask the SS drivin Chem-E

I run at 35 per sticker on drivers door frame and hate it. The car on hot days goes up to 38 and runs like a lumber wagon on rough roads. I would like to see a 16" wheel with a larger sidewall to obsorb the chuckholes without bending the wheel so we could run less air. I think the smaller the sidewall of a tire the more air is needed in case we hit a hole in the road. this way it won't dent the rim.
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Running at 42 cold - makes the road noise a bit louder but maximizes my mileage.

I have factory 17" wheels and I run 41 cold in all tires. Sidewall states 44 maximum. I tested and I do get better gas mileage. The ride is not that much rougher to me or my wife.

The FAA mandates that all aircraft tires be filled with Nitrogen for their consistency and moisture resistance.

I just put Nitrogen in my 2006 HHR. I am running BFG Traction T/A 215X50X17. The car seems to roll better, and possibly smoother but I have not noticed anthing related to fuel economy. I went to a tire shop and had it done for $10 per tire. Their claims were: (1) keeps tire cooler (2) keeps tire interior drier (3) more consistent pressure due to larger molecule in Nitrogen not as prone to leak out. Just 2 cents worth.

32psi all four tires on mine. Regular old free air.

I am running 38 PSI cold and it gets to about 41-42 PSI hot... I believe the sidewalls said 45 if I remember correctly so I am trying to get the max PSI while keeping under the max recommended for the tire.

I plan to upgrade the tires before long anyways with the winters we have here in IL.

I know this isnt directly UNSW related, but would anyone be able to tell me if Basser have internet in the rooms?

Wow, don't know how you got from UNSW to HHR tire pressure, but the answer appears to be yes:


The internet connection in your room will allow you to communicate with your friends, tutors and lecturers, and give you free internal access to the teaching resources placed on-line by your lecturers. It also connects with the learning resources of other universities and all the materials available on the web.
http://www.kensingtoncolleges.unsw.edu.au/colleges/basser/Basser_supportingStudies.html

Google is your friend. :thumb:

We have been over this in a few other threads.

A quick summary/update since my hypermiling started.

If its free (nitrogen) or near free, use it. If you have to pay anything more than a few bucks, don't bother. Since I've been getting 40/32 or 41/29 Hwy/city I think I'm a resonably credible soure on mileage.

2008 HHR SS No mods, 87 octane 8000 odo miles tire 34/35psi cold. I think 40psi cold is the max on the side walls. My ride is rough enough in the city. Wy go higher?