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Discussion Starter · #1 ·
Besides changing tire size to make the Odometer accurate, is there any other way? Can a gear be changed or can it be adjusted with GDS?

Thanks,
KindOldMan
 

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Surely you understand the implications of a user adjustable odometer? :surprise:

No doubt it is possible, but no one who knows how shouldn't or wouldn't tell you.

Is it possible you meant speedometer? That would make more sense for tire or gear change.
 

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Discussion Starter · #3 ·
Surely you understand the implications of a user adjustable odometer? :surprise:

No doubt it is possible, but no one who knows how shouldn't or wouldn't tell you.

Is it possible you meant speedometer? That would make more sense for tire or gear change.
LOL! Yes I do understand the "implications". :grin2:

I do mean the odometer. Not to roll it back or anything like that but to affect how it reads going forward. I understand why car companies deliberately set them to under read - they want to avoid a class action lawsuit. In my case, it is about 2.6%. I know I can run a tire with a smaller circumference and make it accurate, but I was just curious if there was a way in GDS to set an offset factor or modifier to correct it. GDS is a dealer only software (supposedly) so it wouldn't be considered "user adjustable".

I was just curious if I could take it to the dealer and he could correct it.

Thanks,
KindOldMan
 

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You could also run it with less tire pressure so the tire is smaller and would be more accurate. Also, I don't think there is any adjustment they can make.

I believe that they do purposely set it lower because maybe the tires come in smaller (standard tolerance is often a +/- a few percent) or if the tires wear down a lot, causing the diameter to shrink. Some tires may have thicker treads so that when it wears down, the tires become much smaller than other tires.

I wouldn't worry about it as much. Just keep it in mind when you're driving, esp when you are near/above speed limit.

If you feel guilty, put your car on blocks and run the car until the odometer is increased by 2.6%. 2.7% to account for your error in measurement. Never can be too sure.
 

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Odometer runs off the vehicle speed sensor (AKA Output Shaft Sensor) and is not adjustable. As you noted, smaller tires will correct the error. On my car, it was 3.5% under and I actually knocked it further off of reality by fitting larger tires. Now it's off by over 5%. I leave it that way and enjoy the "10 year 105450 mile warranty" afforded by the inaccurate odometer.
Welcome to the "I checked the odometer and it's way under" club. There are a lot of pearl-clutching drama students in this world who "hand calculate" their fuel economy and then clutch the pearls and collapse when the dash mpg number is higher then the number scribbled on the gas station receipt. When you correct the odometer, the dash mpg isn't all that far off. But that doesn't stop the hysteria. I relish the drama - it's like a soap opera without commercials.

The only time an underclocked odometer shoots you in the foot is when you get paid by the mile (IRS filing, employer recording, etc) and you end up getting shorted around 3%. If it's for figuring mpg, just take your odometer reading and multiply it by 1.026 and use the result to divide out the fuel added.
 

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Besides changing tire size to make the Odometer accurate, is there any other way? Can a gear be changed or can it be adjusted with GDS?

Thanks,
KindOldMan
To what end? What do you hope to achieve by "improving" the accuracy of the odometer? How did you determine it wasn't already accurate?
 

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No need to change tire size. Just wait until it is about time to get new ones. The tire will have worn down and the odometer will closely meet your desired accuracy. Yes. The odometer and the speedometer will vary that much over the life of the tires. Just sayin' . At what point in the tire life would you expect the odometer to be right on?
 

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So let's recap. So far, we have recommendations to replace the tires with a possibly incorrect size, run the tires under-inflated, or drive on bald tires. Maybe it's just me, but none of these options sound like a particularly good idea.
Sorry if I didn't make myself clear. What I was trying to get across is that the calibration is constantly changing as the tires wear. I wasn't suggesting to drive on bald tires. But 2/32 is the legal limit on tread wear in most states.
 

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Wait, should the garage doors be open or closed when I'm doing this? I'm afraid of doing this ALL wrong.

Sent from my SM-G930P using Tapatalk
 

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Wait, should the garage doors be open or closed when I'm doing this? I'm afraid of doing this ALL wrong.

Sent from my SM-G930P using Tapatalk

If you have to ask, I'd suggest closed doors...:p
 

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Discussion Starter · #13 · (Edited)
Odometer runs off the vehicle speed sensor (AKA Output Shaft Sensor) and is not adjustable. As you noted, smaller tires will correct the error. On my car, it was 3.5% under and I actually knocked it further off of reality by fitting larger tires. Now it's off by over 5%. I leave it that way and enjoy the "10 year 105450 mile warranty" afforded by the inaccurate odometer.
Welcome to the "I checked the odometer and it's way under" club. There are a lot of pearl-clutching drama students in this world who "hand calculate" their fuel economy and then clutch the pearls and collapse when the dash mpg number is higher then the number scribbled on the gas station receipt. When you correct the odometer, the dash mpg isn't all that far off. But that doesn't stop the hysteria. I relish the drama - it's like a soap opera without commercials.

The only time an underclocked odometer shoots you in the foot is when you get paid by the mile (IRS filing, employer recording, etc) and you end up getting shorted around 3%. If it's for figuring mpg, just take your odometer reading and multiply it by 1.026 and use the result to divide out the fuel added.
LOL! Too Funny! Unfortunately, my car has a salvage title so I doubt Hyundai is going to honor any warranties. My employer does pay for my considerable "on the job" mileage and I have a personal side business that I do report mileage to the IRS for. And while I can just multiply by 1.026, I try to use photos of the odo with "dated material" for proof.

Also, did you mean "lower" above ? (see bolded & underlined)

As always, I appreciate your valuable insight.


To what end? What do you hope to achieve by "improving" the accuracy of the odometer? How did you determine it wasn't already accurate?
Make more $$$ and have a larger tax write off for my personal business.

Multiple >100 mile highway runs tested against the mile markers and then averaged together. BTW, there was very little variation, always 97.4.


I didn't mean for this to get out of hand. I am going to run a smaller, narrower tire (specifically a 175/65r15), properly inflated, and enjoy the increased paycheck, the better ride, the cheaper tires, the accurate odo, and the increased mpg - both indicated and actual. :grin2:

Thanks,
KindOldMan
 

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Also, did you mean "lower" above ? (see bolded & underlined)
Higher will usually trigger the tantrum. The hysteria ensues when the dash MPG reads "27.8" and the very nervous very trepidatious mathematician divides odometer miles by gallons and gets a number like "26.9". After a few minutes in an oxygen tent and a hit of thorazine, they're ready to post online about this being an obvious conspiracy, with Hyundai employing entire teams of engineers to write software code that counts mpg too high. The same team is tasked with changing the "distance to empty" so that it reads "500" when you buy the car and then "200" when you put gas in it and then "---" when you get down under a quarter tank.
I'm an old fart - I don't have enough time left to worry about these things. I do confess to "hand calculating" at each fillup but I round the odometer up 5% (205-60-16 tires installed). If it says "360" on the odometer, I add 18 (which is 5% of 360) and divide 378 by the gallons used. No stress. Blood pressure normal. No pandemonium. Life goes on.

Multiple >100 mile highway runs tested against the mile markers and then averaged together. BTW, there was very little variation, always 97.4.
You can also use google maps and see the same result. The under-reporting is very consistent.

I didn't mean for this to get out of hand. I am going to run a smaller, narrower tire (specifically a 175/65r15), properly inflated, and enjoy the increased paycheck, the better ride, the cheaper tires, the accurate odo, and the increased mpg - both indicated and actual.
The indicated mpg goes up a little bit, but using a tire with a smaller radius will lead to an artificially high mpg number. If the smaller tire rolls 880 times per mile and the larger "correct" tire rolls 870 times per mile, the car is counting 870 rotations as "1 mile" when it needs to really count 880. Not to worry - the actual difference is little more than a rounding error.
If looking at a smaller tire, remember to confirm the load rating is adequate for the Elantra.
 

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Discussion Starter · #15 ·
The indicated mpg goes up a little bit, but using a tire with a smaller radius will lead to an artificially high mpg number. If the smaller tire rolls 880 times per mile and the larger "correct" tire rolls 870 times per mile, the car is counting 870 rotations as "1 mile" when it needs to really count 880. Not to worry - the actual difference is little more than a rounding error.
If looking at a smaller tire, remember to confirm the load rating is adequate for the Elantra.
My only goal is to make my odo accurate (not my speedo or my "indicated" mpg) so I don't have to figure what 2.6% of XXX miles is or multiply by 1.026. In my case, for my odo to be accurate, I need a tire that does 841~842 RPM. The 175/65r15 does that (yes I know RPM changes with tread depth but that is true for both tires - so that's a wash). In my case, the smaller tire is the "correct" tire. The stock tire (the 215/45r17 does ~820 RPM). Whether or not the smaller tire creates an artificially high mpg number on the onboard computer - I don't care, I don't use it - hence the desire to make my odo accurate.

The load index on the OEM tires is 87 and the tire I am going to use is 88, so I should be ok there.

Thanks again dmlexpert! I like your humor!

KindOldMan
 

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I could be wrong, but modern speedometers and odometers are run off a pulse or clock signal. In some cars it's an analog pulse and in others it's a digital one from a microprocessor, computer or some other means.

Most cars with ABS have a computer that knows rpm and speed. I believe this signal can be used in some applications. Since I am new to Hyundai cars, I do not know for sure which version they use.

Alternately, if you could "hack" the firmware used for the displaying and recording of the odometer or speedometer, then it would be "easy" to adjust how you see fit.

I am fairly certain that the old days of cable actuated speedometers rotating gears are long gone. :laugh:

So as impractical as it seems, tire size would be the best way to manipulate teh accuracy of any odometer.
 
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