Tazer , tire size change not effective for speedo

[stingrey]

Hi,
I have a new Tazer JL mini. Updated immediately to firmware 11.4 4.
I bought it for many of it's features but initially for changing standard tail lights to LED tail lights (Oracle).
I also use about 10 more of the vehicle and live settings.
Before I get to far I'll let you know I always perform a full reboot and 2 sleep cycles after changing a setting and all other changes I have made 'stick' and function as expected.

Issue:
I figured I might as well change the tire size to correct the speedometer. It's been off by about 2kph (low) for about the last year. OEM mud terrains are wearing down.
I used the Tazer and changed it from factory set 33.01" to the measured size of 31.75".
This change actually worked and matched the speedometer to the GPS speed, for the 35km trip to the office. On my return home later that day the speedometer was reading 3-4kph lower than gps.

I have unmarried and remarried the Tazer a few times. Always the same results.

I have an email thread going with z-automotive. They have most recently asked me to try leaving the tire size set at the measured size, remove the tazer and plug the harness back into the security gateway.
I have done this but it is not helping.
And of course, while the Tazer is disconnected I can't use its full amazing powers. ?

Tire pressures are all 40psi and the measured diameter is 31.75"

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[Mr._Bill]

Try measuring from the center of the wheel to the ground and doubling it. The number will give you a starting point to work from. It will need adjusted until correct.

When checking the GPS against the speedometer, don't connect it to the USB port in the truck.

 

[stingrey]

Try measuring from the center of the wheel to the ground and doubling it. The number will give you a starting point to work from. It will need adjusted until correct.

When checking the GPS against the speedometer, don't connect it to the USB port in the truck.

Thanks for the tips...appreciated
I have tried a few programmed tire sizes and my phone was not connected by usb. I also use the GPS in my Garmin Fenix 7x.
Who knows, maybe all these GPS devices are wrong.

The weirdest part is, before I got the Tazer the difference was only ~2kph, driving 100kph.
Changing from the OEM 33.01" setting to actual tire size of 31.79" should never have increased the difference to >3kph. It doesn't make sense.

I think I may end up unmarrying to set everything back to stock, remarry to set my tail light to led and just leave it for a while.

 

[jav_eee]

You don’t need the tazer for the oracle lights. They have built in resistors to function properly on factory halogen equipped vehicles.

As for the tire size: I had to play with my measurement until it was accurate. It was not what my actual tire measurement was.

 

[stingrey]

You don’t need the tazer for the oracle lights. They have built in resistors to function properly on factory halogen equipped vehicles.

As for the tire size: I had to play with my measurement until it was accurate. It was not what my actual tire measurement was. This should not be necessary

Re: Lights - Yes I needed a programmer.
Like many , my Oracle Tail Lights didn't work right with the provided resistor and I would need more resistors added. For me the reverse lights would not work and the red lights were flickering. Then the right tail light went out completely. All cases with the Oracle Flush Mount tail lights are not necessarily the same. It's pretty well documented. I'm sure you're aware.

 

[Toro34]

Thanks for the tips...appreciated
I have tried a few programmed tire sizes and my phone was not connected by usb. I also use the GPS in my Garmin Fenix 7x.
Who knows, maybe all these GPS devices are wrong.

The weirdest part is, before I got the Tazer the difference was only ~2kph, driving 100kph.
Changing from the OEM 33.01" setting to actual tire size of 31.79" should never have increased the difference to >3kph. It doesn't make sense.

I think I may end up unmarrying to set everything back to stock, remarry to set my tail light to led and just leave it for a while.

Keep in mind that GPS isn't necessary as accurate as ppl think. It basically works by taking timestamps from different satellites, how long it thinks it took to receive the data, comparing them to known current location, doing some math and giving you a number.

If it is cloudy, there are buildings or trees in the way, or just fewer satellites available based on the time of day and your spot on earth, these will affect your GPS accuracy

Once you start changing tire sizes with the Tazer, your speedo is adjusted by a percentage. If you are off by 2kmh at 100kmh, then that is a 2% difference. Also, just because you might have the correct measured tire size set in the Tazer, doesn't really mean that is what you will be travelling, but you can 'adjust it out' by increasing the tire size in small increments on the Tazer and verifying over and over.

Have you measured all 4 of your tires and taken the average? You could be working with a single tire that is smaller than the rest? There are honestly so many variables...

You will never be 100% accurate, but anything ~2% is pretty much acceptable.

Try setting your tire size to 32.45 and see what that gets you.

For stock tire sizes, I prob wouldn't bother deviating from what Jeep set at the factory unless the inaccuracy was very noticeable. I'm not even sure that the default Tazer setting of 33.01 is actually what it's set from at the factory? Maybe just a starting point in the configuration software

 

[jav_eee]

It's pretty well documented. I'm sure you're aware.

Actually I wasn’t aware but now I am. I prefer the OEM lighting so I usually pass over the oracle posts.

 

[Dickster]

Pull the tire off and measure the circumstance and divide by Pi 3.14.
This will give you actual tire height.
You will need to do this with no load on the tire.

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