ECO-Fit DiscussionThreads discussing the pursuit of ultimate economy, hypermiling techniques & maximizing your MPG
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Dumb question, but you didn't mention this. When was the last time you changed your oil?
Was this a gradual decline, or did your mpg drop all at once? If all at once, were there any changes around that time? For example:
Different driving habits, routes, traffic patterns?
Change in gas station or gas formulation by your station?
Change in weather?
--Barry
I change the oil at 3k on the money. It was a gradual decline and I tend to use the same gas stations. When on long trips I was close to 400miles on the tank now im lucky to get 265. The only thing I have done differently was switch to a synthetic blend motor oil
You are the problem(no offense) because technique is key.
- drive the speed limit or less
- shift at 2.5k or less
-accelerate moderately(this is not a race car)
-P&G
-DWL
-DWB
-tire pressure to side wall max
- and lots and lots of practice.
Got the automatic not manual. I'm new to this what does the abv mean?
I change the oil at 3k on the money. It was a gradual decline and I tend to use the same gas stations. When on long trips I was close to 400miles on the tank now im lucky to get 265. The only thing I have done differently was switch to a synthetic blend motor oil
The gradual decline makes me think of either a buildup (perhaps on the MAF-- I'm assuming we have one, but my Helms manual is down in the garage-- or on the plugs) or a deterioration (of seals, rings, timing, etc.). It would be interesting to put an OBD2 scanner on your car and on one that is getting better mileage and compare them under similar conditions.
I'm sorry, but I can't think of anything obvious. I'm only a mechanic by virtue of working on all of my own cars and those of a few friends.
- I achieved 46643miles out of them until they were at 3/32 tread life left, not at the wear bar but too close for comfort.
- I purchased the car on July 31, 2007 new with about 30miles on it.
- for about 12K I had the tires at 60-65psi, for about 10k I had the tires at 50-55psi and the rest or first part of the tires life they were at the recommended 32 psi.
- I had the tires rotated and balanced at least 5 times.
- Stock tire was Dunlop SP3 with a side wall max of 51psi.
- The guy at the tire place said they are only good for 20k(not sure if that is a true statement) and was surprised at what miles I have squeezed out of them.
The new tires are Kuhmo LX platinum with 60K warranty and a side wall max of 51psi. I plan on pumping them up to 70-75psi assuming I can stand the ride quality. I hope these will glide like sliding on ice.
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stock and lame
slow and steady wins the race
Well, I have driven about 40miles today and boy are these things sticky!
I can't even roll out of the garage now unless I stick my foot out for a couple of pushes.
Even then I still have to get out and push at a spot where I was able to coast over at <5mph before I get out of the neighbor hood.
At first I thought it was because the installers only put them at 40psi(which actually surprises me that they put it that high). However, I drove to the nearest air pump and inflated them to 75psig. I have to say that the ride is not as harsh as the last tires and they were only at 65psig. Maybe I need to increase it to 80-85psig. I have read that I should expect less mpg for about 1-2k but I was hoping that wouldn't be the case.
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stock and lame
slow and steady wins the race
I'm curious about tires wearing in the center as a result of the higher pressures. The hypermilers claim tires still wear evenly since steel belts keep the tire surface flat. One poster said he's seen tires inflated at higher pressures for use in races wear out faster in the middle.
Anyone have any data for tires used only in streets?
Tires used on the street will also wear out in the center at higher pressures. The steel belt in the tread 'bows' with higher pressure with high point in the middle.
I rarely get more than 20,000 miles per tire because the center wears out while the edge still has 4/32" tread depth. I rarely slow for corners so that does help but even then the most contact is centered rather than on the edge. And yes, reducing the tire contact patch does reduce rooling resistance which improves mpg. Thats why narrower tires yield better mpg than wider ones of the seame diameter.
Anyone with 4/32" tread left on the tire whether on the edges or center should have already changed tires if you are concerned about safety in wet weather.
Basically you can overinflate tires and get away with it for a period of time.
Since gas is under $2 a gallon what is the point?
Low tire pressure is definitely bad for handling and mpg.
Too high tire pressure has it's limitation as well. If you wear out the tire faster you have to weigh the cost of tire replacement against whatever more mpg you can get.
You can get a noisier or rougher ride with higher pressures- something you will have to live with depending on the quality of the roads you travel on.
bryanfor311 - I don't believe your are well informed or experienced on tire pressure.
Safety is why I replaced the tires at about 3/32-4/32 tread depth. It felt like I wasn't getting as much grip as before and then hydroplaning was a concern.
Sid 6.7 - because I wanted too Didn't need to but I wanted to try and keep the same mpg numbers. It was too cold to push this morning. I really felt and saw the decrease in mpg for these tires on the morning commute. I was down to 54mpg vs. 65mpg on the old tires.
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stock and lame
slow and steady wins the race
bryanfor311 - I don't believe your are well informed or experienced on tire pressure.
Safety is why I replaced the tires at about 3/32-4/32 tread depth. It felt like I wasn't getting as much grip as before and then hydroplaning was a concern.
Sid 6.7 - because I wanted too Didn't need to but I wanted to try and keep the same mpg numbers. It was too cold to push this morning. I really felt and saw the decrease in mpg for these tires on the morning commute. I was down to 54mpg vs. 65mpg on the old tires.
Kumho uses soft compounds...kinda goes with my earlier reply to you.
So of course your ride will not be as harsh even with the high pressures, but you certainly should not be over inflating by THAT much...thats very dangerous. You'll definately pop if you hit a big enough pothole.
With the softer compound comes more grip and more tire contact on the road...as you already know too. hehe. There's really nothing you can do at this point, besides go back in and get different ones.
if you've noticed, OE tires for a majority of common cars on the road are of harder compounds...usually so Manufactuers can claim higher MPG ratings, and sometimes they're cheaper for them to buy too.
With older cars and friend's cars, we no longer get kumho (street type tires) because they're compounds are so soft that sometimes you'll really ride on the sidewalls on hard turns and you'll certainly tear em up (literally) if you take em to the track.
Well, I stand corrected you are well experienced. I do wonder about the informed part though. I really don't have a whole lot of room to talk but from my own experience and the information that I have gathered, the higher tire pressure, even higher than 80psi, has been proven to handle better and last longer for ECO driving conditions. My last set of tires I had at 66psig and that was with two tires having a patch. Even when I had a screw in my tires at 60psi there was no problem or blow out.
With that said, I did NOT say 80psi is optimal for AutoCross or drag racing which are two completely different sports. Yes, sports. No one drives or rather I should say, should drive like that in a commuter car.
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stock and lame
slow and steady wins the race
Because I drove 45K in 15months. The Dunlops were a few bucks more but I need something that will last longer than 15months . After these Kuhmos break in I hope they do just as well.
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stock and lame
slow and steady wins the race
PBandH
i'm not arguing a tires ability to decrease rolling resistance with increased air pressure and thus increase gas mileage. I was merely concerned about your safety with severely overinflated tires.
Well, they are at 80psig now and I have no problems with them cornering even on the wet pavement, experimented with an off ramp and several corners. I wouldn't have believed it until I tried it with my last set of tires. We, yes we(everyone here), will find out what these tires are good for at the inflated psi. I want to use what works best. That means if 80psi is too high then I will gladly lower them. I am not saying what I am doing is right but I am merely experimenting. From my experience and what I have read about higher seems to be better for hypermiling.
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stock and lame
slow and steady wins the race
). However, I drove to the nearest air pump and inflated them to 75psig. I have to say that the ride is not as harsh as the last tires and they were only at 65psig. Maybe I need to increase it to 80-85psig.
I have read that I should expect less mpg for about 1-2k but I was hoping that wouldn't be the case.
Linear Mode
