Anyone overcoming gas prices by hypermiling?

[ERD50]

Is the maximum PSI printed on the tires themselves an unsafe pressure? Would that PSI cause uneven wear on the tires, does anyone know?

Quote:

Originally Posted by Leonidas No, the max is okay.

Leonidas, are you certain that is good information?

The way I look at it - the tire is one component; the car, it's weight, suspension, etc, are others that make up a system. I don't think it is correct to take one specification of a component, and assume it is good for the whole system.

Car suspensions are designed with the PSI that is on the sticker. Going beyond that range may not damage the tire, but it could adversely affect handling of the car, and make it less safe. I wouldn't do it unless the manufacturer said it was OK, and I personally think you should tell any passengers that they are in a car that has been modified past it's design limits. Maybe they'd rather walk.

My tires are rated for 170mph - but I doubt my brakes are! And the cylinder head bolts are probably rated to take 200 ft-lbs - but that is *not* the correct torque spec for the cylinder head. I think you are making potentially dangerous assumptions.


-ERD50

[Leonidas]

Quote:

Originally Posted by ERD50 Leonidas, are you certain that is good information?

Multiquote is not working for me today, so you'll have to go back to the first page of the thread to see my original post where I said overinflation was not a good idea due to handling, safety and wear issues.

I am certain that inflation up to maximum PSI is okay for tire wear, but that you have to fill them cold and be aware of temperature changes from environmental factors to avoid overinflation.

You are correct that almost everybody should run their tires at the recommended PSI (look in the owner's manual). Personally, I tune my tire pressure by adjusting it by a few PSI at a time until I find the spot where ride and handling feel right. It's usually very close to what the recommended PSI is. A couple of pounds of pressure difference can make a vehicle feel and act very differently.

However, when I was w*rking I usually kept my tires at, or very close to max PSI. It significantly improved handling, but I felt every little bump in the road. It also tended to track along with grooved pavement (not a good thing to have happen in curves at 140). But we ran V or Z rated tires and I also had lot of training and experience in how far I could push the car at different speeds and with that much inflation in the tires.

I have blown whole tires stores full of sidewalls over the years, but those all were because I got overly aggressive in a turn and my apex point was a curb that I kissed a tad too hard. The only negatives that I ever worried about were that tires with high inflation can break free from the pavement if you push them hard enough, and (I believe but can't prove) that they tended to hydroplane easier. The first wasn't too big of a problem because you had to be really aggressive in shifting weight around to make them break free - like a J-turn - and there were times when I needed to do some of things I could do when I aggressively shifted the car around and made the tires break free - like a J-turn. The hydroplaning thing scared the crap out of me though, and if it was raining I usually dropped the pressure down a couple of PSI at a time until I felt comfortable pushing the car a little.

I see your points and agree, although I think that anyone on this forum who is looking to boost gas mileage while talking about "imagining an egg on the accelerator pedal" is very unlikely to get themselves into trouble by riding on fully inflated tires. And if they are, then they probably aren't paying attention to anything I say about tire inflation - or saving gas.

[ERD50]

re - ERD50 earlier post...

Quote:

Originally Posted by Leonidas so you'll have to go back to the first page of the thread to see my original post where I said overinflation was not a good idea due to handling, safety and wear issues.

Sorry, you're right - I missed it as we were on page 2 already.

-ERD50

[TromboneAl]

The manual for our '02 Echo says to inflate to 35 PSI. When I bought our high performance tires, I was told it was OK to inflate them to the max, 44 PSI. Told I would get better mileage and the handling would be better. "What's the disadvantage?" I asked, and was told "Well, TromboneAl, the only disadvantage is that the ride will be rougher." The ride is fine, and we get 41-44 MPG routinely (mostly highway).

The other thing we do, that I've mentioned before, is drive 55 most times.

[tightasadrum]

I'm no longer thinking in mpg terms; it's more of fpm, as in fillups per month. Before I stopped w**king and commuting 135 miles per day I filled up the old Camry twice a week. Now it's twice a month, maybe. Just shows that not driving is better than higher mpg. It helps to live in a smaller community too; trips are shorter. And I find it useful to combine errands as much as possible. Being well invested in commodity futures that include oil makes the whole package a little easier to stomach.

[windsurf]

And I find it useful to combine errands as much as possible. Being well invested in commodity futures that include oil makes the whole package a little easier to stomach.

I jumped into Vanguard energy a couple of years ago and have watched the 25k smidge double. I wish I would have gone bigger. But, like you, I look at that gain as mitigation of the pump pain. Do you think energy stocks will "pop" one these days (as in bubble)?

[tightasadrum]

Quote:

Originally Posted by windsurf And I find it useful to combine errands as much as possible. Being well invested in commodity futures that include oil makes the whole package a little easier to stomach. I jumped into Vanguard energy a couple of years ago and have watched the 25k smidge double. I wish I would have gone bigger. But, like you, I look at that gain as mitigation of the pump pain. Do you think energy stocks will "pop" one these days (as in bubble)?

Yes. But the big question is when. But isn't that the whole reason for re-balancing your portfolio? My problem, and it sounds like yours too, is that I would prefer to have an even higher percentage in a well diversified commodity fund, so re-balancing some money out of the fund goes counter to my overall objective for now. But of course the risk is there that I may lose the huge runup I've got on paper. You plays your cards and takes your chances I guess.

[NotReady4Purple]

It's spring. I'm bicycling... :-) That gets me down to one fillup per month.

[Zathras]

For me, drafting behind trucks is not worth the added danger to myself or others.
I will follow trucks at a standard distance and do a lot of other things that don't endanger me.
I find the biggest single helper is to use a light foot on the accelerator and brake.

[UncleHoney]

Quote:

Originally Posted by Zathras I find the biggest single helper is to use a light foot on the accelerator and brake.

So right you are Zathras.

DW's car has a trip computer that gives a direct readout of fuel mileage. It's amazing what just a little restraint on the accelerator yields in fuel savings. Even at highway speeds small changes can save big bucks over the life of a tank of gas. I've found I can easily beat the cruise control, especially when you encounter long grades. Letting the car slow down just a little till you top the hill really saves gas. Easing off the gas on the way down a hill instead of picking up speed by driving down the hill adds up too.

I like to avoid the packs of cars on the Interstates that require frequent speed changes too.

I always like to drive like there's a raw egg between my foot and the accelerator. Easy does it. And learn to anticipate road conditions ahead and make small changes in speed to avoid using the brakes.

[Milton]

Okay, let's consider run the numbers:

• Savings achieved through better mileage: variable, but let's say an average of $200 annually multiplied by, say, three years (before an accident happens);
• Cost of destroying your vehicle in a rear-end collision: variable, but let's say an average of $15,000 (only incurred once in a lifetime);
• Cost of funeral expenses due to being killed in said rear-end collision: variable, but let's say an average of $10,000.

So, CBA suggests the potential direct financial costs ($25,000) outweigh the potential financial benefits ($600). And that's not even considering the non-financial costs, or the indirect financial costs.

No thanks!

[Notmuchlonger]

Need to setup those computer controlled cars for highway driving. That way traffic would be smoother. Drafting would be possible. Less traffic jams would increase mpg.

[Bestwifeever]

Quote:

Originally Posted by Milton Okay, let's consider run the numbers: Savings achieved through better mileage: variable, but let's say an average of $200 annually multiplied by, say, three years (before an accident happens); Cost of destroying your vehicle in a rear-end collision: variable, but let's say an average of $15,000 (only incurred once in a lifetime); Cost of funeral expenses due to being killed in said rear-end collision: variable, but let's say an average of $10,000. So, CBA suggests the potential direct financial costs ($25,000) outweigh the potential financial benefits ($600). And that's not even considering the non-financial costs, or the indirect financial costs. No thanks!

Early inheritance and bonus life insurance for heirs and beneficiaries: priceless.

[Leonidas]

I may have to correct myself. I can't find anything that says overinflation causes hydroplaning, but my non-technical feeling is that it should. Back when I had a j*b we would push the envelope pretty hard on driving and I hydroplaned on all four tires several times. There's nothing like going down the interstate sideways at 80, with no steering control, to make you very sensitive to things like tread wear and tire inflation.

[HFWR]

From the Rubber Association, heh...

Rubber Association - Proper Tire Inflation

Quote:

Over-inflation can be a problem too. An over-inflated tire rides on just the centre portion of the tread. The smaller contact area means reduced grip on the road, leading to a harsh ride, handling issues (such as steering and stopping problems) and increased wear on tires and suspension components. Seventeen per cent (17%) of vehicles in Canada have at least one tire that is over-inflated by 20%.

[cute fuzzy bunny]

Bunch of bad ideas in general. Mostly stuff that saves you a few pennies now and costs you more later on.

Many vehicles are designed for a specific tire footprint and inflation rate. Changing that may result in changes to handling and braking. Overinflation wears your tires out in the middle fast while leaving tread unworn on the edges.

Pulse driving wears on a number of driveline components.

Tailgating can get you dead fast. You need to get within 10 feet of the truck in front of you to get a mileage boost. At that speed, you'll need to keep adjusting your speed to avoid crashing into the truck and keeping to within 10 feet. That on-off-on-off the gas can end up costing you mileage.

Eliminating unnecessary trips and driving under 55mph with properly inflated tires, avoiding any leadfooting and observing the traffic ahead of you and modulating speed gently to suit will offer pretty good gas mileage.

I just adopted a great strategy for picking up 7mpg. I started driving our Rav4 as my primary car instead of the Pilot.

[free4now]

My manufacturer recommends 33psi, but I find I get the best handling at 42psi. I used to always dread having to convince servicepeople that I knew what I was talking about and 42 was the right pressure for my tires, but recently I found a great workaround: I just made my own sticker that says 42psi and stuck that over the manufacturer sticker on the inside of the door and in the glove compartment.

Another thing I do for mileage is get regular alignments. Most people don't know that for $150-$200 you can buy a lifetime 4 wheel alignment warranty for your car. I bring the car in around every 10-15k miles, and every time they find something slightly out of spec. It's a bit of a hassle but also saves on tires because you get full warranty miles out of them.

Drafting? No friggin way.

[Bestwifeever]

Re drafting behind a semi on the highway--wouldn't that hurt the semi's MPG to be pulling you along? I could see some sudden stops on the truckdriver's part to deal with that problem....

[Notmuchlonger]

Quote:

Originally Posted by Bestwifeever Re drafting behind a semi on the highway--wouldn't that hurt the semi's MPG to be pulling you along? I could see some sudden stops on the truckdriver's part to deal with that problem....

No, because you are in the air the semi already cleared. (which is a super simple explanation)

Thats the problem sudden stops.

[Bestwifeever]

Quote:

Originally Posted by Notmuchlonger No, because you are in the air the semi already cleared. (which is a super simple explanation) Thats the problem sudden stops.

Ahh, I see--thanks. I was misunderstanding.