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Discussion Starter #1
So got my insight 2 weeks ago silver 02 m/t 186k miles new ima from dealer a year ago. I've learned lean burn and am not new to hypermiling techniques. My first tank netted me 51mpg I was extremely disappointed as I drove very conservatively. Unfortunately the car has 17"aftermarket wheels and low profile tires. I do have them pumped to sidewall Max. Could the wheels make a 20+mpg difference? I know the factory ones are 14 and very light. Also I have a check engine for the cat converter p0420 but the power doesn't seem to be affected. I'm using torque app for engine monitoring. Any opinions?
 

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What size tires do you have now? The first thing I would check is the number of revs/mile and compare to the stock tires. If your tires are larger, the revs will be less. So the car will "see" less miles == less mpg reported.
 

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Discussion Starter #3
205/40/17 is the tire size
I did do a gps speedometer test and the speedometer is still accurate somehow.
 

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That seems like a fairly wide tire. Other tires in the exact same size as the original probably reduce the mpg by 7-12 mpg, yours might be hurting you even more than that.

Are you using the climate control in the full auto mode? Are you using the air conditioning? Does your car shut off at stops?
 

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205/40/17 is the tire size
I did do a gps speedometer test and the speedometer is still accurate somehow.
Since your tires are of such low profile, the difference from the stock diameter isn't all that great. So, the speedometer error would not be very large. This says nothing about the rolling resistance of the non-stock tire which I would bet is costing you a lot of MPG.

Use the "User CP" button above to edit your location. If you are in the right area you might be able to convince someone to do a test tire/wheel swap on a Saturday morning. I'd venture you would notice a ton of MPG difference.
 

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What size tires do you have now? The first thing I would check is the number of revs/mile and compare to the stock tires. If your tires are larger, the revs will be less. So the car will "see" less miles == less mpg reported.
This is in fact the case by about 5%. The stock diameter is 22.44" while the aftermarket diameter is 23.46" . Good call;)

Rolling resistance difference plus diameter distance could account for a fairly large hit.
 

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My car is stock and I have changed tires twice in the last few months. When I got my car late last year it had tires that were in mediocre condition, cracky and if I remember the date codes were some time in 2006. I don't like to mess with tires in that condition & age. At time I had been lurking here some and everybody kept talking about RE92's. I priced them and any thing else in the correct size, which happened to be Khumo. The Khumo's were $30.00 less expensive per tire. I discussed them with a good friend, mechanic, and ended up buying them.

I work in a shop and do my own mount & balance and alignment work. When I took the wheels w/old tires off the car I basically lifted them with one hand, very light. When I went to mount the new Khumo's the weight of the tire alone was almost as much as the wheel & tire. I did not think to much about it.

On old tires I was getting in the low to mid 50's mpg. Started driving the new tires, theft rode OK, however mileage started to suffer, almost couldn't break 47.7mpg. Put in new air filter element, correct factory spark plugs still no improvement. Air pressures 40 frt, 38 rear same as I ran in worn tires. Also noticed at times my hybrid battery SOC was not as good at times. When I bought my car it need the battery replaced and bought one from one of the suppliers that had just started putting them together with all new 8 amp hour sticks.

I drove the new tires approximately 3000 miles and 47.7 was making me crazy. Did some more reading here and more thinking and remembering the weight of those heavy tires. Went back to work and ordered a set of RE92's. Put them on three weeks ago tomorrow. Drove out of shop and went to the gas station 1/2 block down the steer, filled up and reset everything as I always do. All of the sudden MPG between 54 & 56 on FCD, my new fancy battery and SOC working better than ever. Still on second tank of fuel since tires and still 54 & 56 MPG.

I was amazed how much horsepower it took to turn those heavy tires. However,when you only have 67hp and you use it to turn the additional weight it robs the car. Also, when I asked the tire dealer if he knew the weight of the tire he looked it up on the spec sheet and told me RE92's were 13lbs each, spec sheet for Khumo's didn't say, my guess 20lbs each.

I have a set of tires sitting in the shop with aprox 3000 miles on them that wil end up on Craigslist.

I'm way happier, and somewhat less crazy.

HTH,
Scott
 

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Discussion Starter #8
Thanks for the replies. I live in Murrieta ca so I'm near upland klr. Your story sounds like what I'm experiencing I bet reducing the weight and width of the tire will free up the power to increase mpg.
 

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Thanks for the replies. I live in Murrieta ca so I'm near upland klr. Your story sounds like what I'm experiencing I bet reducing the weight and width of the tire will free up the power to increase mpg.
Take a look at the avatar of the other contributors like KLR3CYL above. Their approximate location appears on every post. Your one post of location is going to get lost pretty quickly. You need to go to "User CP" and edit your location, on the sidebar;)

Since Scott is close by, perhaps you can arrange a temporary swap of tires and wheels on some weekend, if you still need a demonstration of the potential of the car. My educated guess is that you are losing at least 10 mpg to your current tires.
 

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Yes I sleep in Upland, during the day I'm in Covina, 15 miles further from Murrieta. Also , during the day aim in a shop. If you wanted to drive. Set of stock on your cara swap could be done very quickly, air tools & multiple lifts. If you just want to try driving a different car or comparing driving techniques that can also be arranged.

I also have some friend/customers who live in Murrietta, near the airport. Their car is a 2000, mt, with a/c 293,000. They are bringing it to me next week on the 30th for a hybrid battery swap. Their car is the reason I own one.

Let me know if you would like to do something.

Scott
 

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Discussion Starter #11
Thanks Scott I live by the airport too. Are your friends on this message board? I would like to feel the difference between the two wheels. My car really lugs from a start and I have but don't use my ac. So far on 70 miles of use I'm at 58mpg on the display. A lot better but I feel certain that the wheels/tires are contributing to at least a 15mpg loss.
 

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Thanks Scott I live by the airport too. Are your friends on this message board? I would like to feel the difference between the two wheels. My car really lugs from a start and I have but don't use my ac. So far on 70 miles of use I'm at 58mpg on the display. A lot better but I feel certain that the wheels/tires are contributing to at least a 15mpg loss.
Now you are networking. We all do it:D
 

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This is in fact the case by about 5%. The stock diameter is 22.44" while the aftermarket diameter is 23.46" . Good call;)

Rolling resistance difference plus diameter distance could account for a fairly large hit.
I imagine the extra weight of the larger wheels and tires is taking a toll every time he accelerates, too. Although I have no feel for how much that would be. There could always be other things going on as well, but best to count the obvious things first. :)
 

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The friends are not on the board.

Like I mentioned earlier they are on the calender to bring their car in next week for the hybrid battery. Once that is done I might be able to set you up with them. Or you are welcome to come try mine and swap techniques.

Scott
 

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I concur with the tire swap dilemma...I got tired of the RE92's and switched to Michelin Defender 175-65R14's. The tire is really a great tire. Quiet, very grippy,
excellent in the snow and the rain,and excellent to resist hydroplaning and a 90,000 mile tire....But I've lost about 10 MPG and it's much harder to get into leanburn.

Changing the subject slightly, what is the deal on the RE92's being discontinued? Is it really true?
 

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Changing the subject slightly, what is the deal on the RE92's being discontinued? Is it really true?
A bit hard to say. They are currently in short supply and Firestone dealers have been saying they're discontinued. I recently got some through Costco, but their supply many also be short.

There is a theory that Bridgestone will make another run of this rare tire, when current supplies are exhausted. Who really knows:?:
 

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Changing the subject slightly, what is the deal on the RE92's being discontinued? Is it really true?
A bit hard to say. They are currently in short supply and Firestone dealers have been saying they're discontinued. I recently got some through Costco, but their supply many also be short.

There is a theory that Bridgestone will make another run of this rare tire, when current supplies are exhausted. Who really knows:?:
According to my correspondence with Hunter Leffel at Tire Rack, Bridgestone already has discontinued production of the RE92's in our size. He isn't allowed to release inventory numbers so I don't know how many are left. I do have a way of finding out and plan on looking into that shortly.;)
 

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Yeah. It would be a shame to run out of these tires. But I also think it's insane that we have to possibly stock up on and try to preserve stored copies of these beauties by bagging and all the other things I have read on this site IMO
 
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