Hey everybody. I'm sorry if this topic has been covered already, but I haven't been able to find a good answer yet... I just bought some Duratracs for my '06 LC and decided to upsize a bit (I went to a 275/70/18). I know this will throw my speedo off by 7% or so, which I'm not very concerned about, but I would like to keep my odometer and telemetry (for MPG etc.) accurate. Is there a way to fix this issue? Will a dealer be able to adjust the computer to compensate, or is there something I can do to fix it myself?
Speedo/ Odometer heal for larger tires
- Thread starter derek0177
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- duratrac odometer speedometer
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Slee offroad has something for that. Check it out
Are you saying I can get 112MPG by just adding larger tires? Should have gone larger a long time ago.
Yes because the larger tire is covering 7% more distance. So if you show 15 mpg multiple that by 107% so you really got 16.05 mpg.
I went up to the same size tire and ordered a Yellowbox with the plug and play harness. I had them make the harness 2 meters long so I could string it into my cab. I had a bit of a struggle to understand the programming but I'm sure anyone else would have gotten it easier. They were great to deal with and helped get me sorted out.
Sorry for the horrible joke
No problem I did not know if you were joking or just not a math person. Most 100 owners don't care much about mpg or they would be driving something else.
My tires, 285/75R16, turn out to have a circumference 10% larger than stock, per the mile marker/odometer method. (many trials with low SD. I know, I get bored on road trips.)
It makes it easy to do the math in my head: 60mph = 66mph, 250 miles on a tank of gas = 275 actual miles, 15mpg = 16.5mpg, etc.
It makes it easy to do the math in my head: 60mph = 66mph, 250 miles on a tank of gas = 275 actual miles, 15mpg = 16.5mpg, etc.
One of my favorite features of the Pioneer AVIC-7100NEX is that when you put it on the Map Screen, on the bottom left corner there is a little sign that looks like a speed limit sign with both the speed limit and actual speed.
Since switching to bigger tires (285/75/16), this has been huge. Especially when driving through school zones.
Since switching to bigger tires (285/75/16), this has been huge. Especially when driving through school zones.
I did a Yellowbox correction on my 80 and it did fix the offset for gears/tires very well. It did, however, induce enough lag in the speedo that the cruise control had a tough time operating without surging. That being said, it was a revision it two back of the Yellowbox and newer ones may be better.
Now that I have a 100 with oversize tires, I am looking for a solution as well but am hesitant to go the Yellowbox route again.
Anyone have one of these new units on their 100 and have cruise that doesn't surge? Mine is an '06 just like the OP.
Now that I have a 100 with oversize tires, I am looking for a solution as well but am hesitant to go the Yellowbox route again.
Anyone have one of these new units on their 100 and have cruise that doesn't surge? Mine is an '06 just like the OP.
I don't have any issues with the cruise control.
Ditto - Yellowbox working perfectly here for probably 7-8 months (12k miles).
I second yellow box. Works great correcting my speed for 34's
295/65/18 duratracs. I'm going 68 when speedo says 65 according to the digital "slow down" signs. 3 mph isn't enough for me to worry about.
...via IH8MUD app
...via IH8MUD app
On my old 80 series, and my current 100 series, I've just used the caveman method of "when the speedo reads X, it really means Y" and that has worked just fine for me.
Now that my 17yo son has a 100 series of his own, and he hasn't seemed to show an aptitude for the "caveman method" of speedo correction, I now have an interest in installing one of these boxes on his car. Our temporary stop gap fix has been to install a scangauge II on the top of his steering column w/ the scangauge doing the simple math for him.
There seems to be two schools of thought when installing one of the speedo correction boxes
It appears that method "2" would just alter the output to the V2 combination meter.
I'm leaning toward method "2" as it seems simple and easy to me, but I'm not completely clear on what systems are going to receive a "modified" VSS signal and which systems are going to receive an unmodified signal.
Using method "2"
Now that my 17yo son has a 100 series of his own, and he hasn't seemed to show an aptitude for the "caveman method" of speedo correction, I now have an interest in installing one of these boxes on his car. Our temporary stop gap fix has been to install a scangauge II on the top of his steering column w/ the scangauge doing the simple math for him.
There seems to be two schools of thought when installing one of the speedo correction boxes
1) Insert the box at the speed sensor plug at the transfer case.
2) Insert the box on the speed signal (behind the glovebox) going to the combination meter
It appears that method "1" would alter the V2 (combination meter) & V3 (transmission) circuits at the source.2) Insert the box on the speed signal (behind the glovebox) going to the combination meter
It appears that method "2" would just alter the output to the V2 combination meter.
I'm leaning toward method "2" as it seems simple and easy to me, but I'm not completely clear on what systems are going to receive a "modified" VSS signal and which systems are going to receive an unmodified signal.
Using method "2"
I assume this corrects the speedometer.
I assume this corrects the odometer.
I assume that the transmission will see an unmodified signal (but I really don't have a problem with the current shifts).
What would the ScanGauge see through the OBDII port, modified or unmodified?
What would the cruise control see, modified or unmodified?
Doesn't ABS/VSC/A-TRAC/etc read the speed through the wheel sensors or do they have some input from V2/V3?
Other than the transmission circuit not being modified to adjust the shift points, what are the drawbacks to method "2"?
I assume this corrects the odometer.
I assume that the transmission will see an unmodified signal (but I really don't have a problem with the current shifts).
What would the ScanGauge see through the OBDII port, modified or unmodified?
What would the cruise control see, modified or unmodified?
Doesn't ABS/VSC/A-TRAC/etc read the speed through the wheel sensors or do they have some input from V2/V3?
Other than the transmission circuit not being modified to adjust the shift points, what are the drawbacks to method "2"?
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The Yellow Box plug-n-play harness connects to the output of the transfer case, and that IMO is a much easier option of removing the glovebox and splicing wires. This is upstream of the engine/tranny ECU, so it thinks nothing has changed. The RPM shift points would be the same, only the speed would be different.
I had the YB PnP on my 80 and it worked very well and was simple to install.
I had the YB PnP on my 80 and it worked very well and was simple to install.