Tazer - Increasing Tire Size Not Changing Speedometer

[BLACKMOAB]

I got taller tires by 2”. I’ve increased (and successfully saved) an increased size 6 times in increments and according to GPS it’s not changing the speed on my speedometer - GPS shows 72 mph when speedometer shows 70 mph. I increased the tire size to over 2” taller than what they are with no change to speedometer. The size changes are saving and I’m doing a full reboot after every increase and then making a highway run to check. What could be wrong? I’ve emailed Z Automotive but they probably won’t answer me until Monday.

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[beaups]

I got taller tires by 2”. I’ve increased (and successfully saved) an increased size 6 times in increments and according to GPS it’s not changing the speed on my speedometer - GPS shows 72 mph when speedometer shows 70 mph. I increased the tire size to over 2” taller than what they are with no change to speedometer. The size changes are saving and I’m doing a full reboot after every increase and then making a highway run to check. What could be wrong? I’ve emailed Z Automotive but they probably won’t answer me until Monday.

Are you following the reboot/sleep procedure per the instructions?

 

[Rudolph Hart]

I got taller tires by 2”. I’ve increased (and successfully saved) an increased size 6 times in increments and according to GPS it’s not changing the speed on my speedometer - GPS shows 72 mph when speedometer shows 70 mph. I increased the tire size to over 2” taller than what they are with no change to speedometer. The size changes are saving and I’m doing a full reboot after every increase and then making a highway run to check. What could be wrong? I’ve emailed Z Automotive but they probably won’t answer me until Monday.

My experience with Joe suggests you’ll get a reply tomorrow.

 

[BLACKMOAB]

Are you following the reboot/sleep procedure per the instructions?

Definitely the reboot and I think so on the sleep - start engine, turn it off, open door, close and wait until the dash lights shut down and then repeat those steps a second time?

 

[beaups]

Definitely the reboot and I think so on the sleep - start engine, turn it off, open door, close and wait until the dash lights shut down and then repeat those steps a second time?

Sounds correct. When you go back through the tazer menus is it showing the new size correctly?

 

[BLACKMOAB]

Sounds correct. When you go back through the tazer menus is it showing the new size correctly?

Yes, that’s what’s so frustrating to me. I’ve even tried 3 different GPS apps and they all give the same readings.

 

[Jason Oliver]

Did your speedometer match the GPS programs before you increased tire size?

 

[BLACKMOAB]

Did your speedometer match the GPS programs before you increased tire size?

It was exactly the same - speedometer read 70 and GPS read 72.

 

[BLACKMOAB]

By the way, my Tazer came with the 11.1.5 Firmware and I updated it to the 11.1.7 version when I got it. Could that have screwed something up?

 

[BLACKMOAB]

Since no one is responding or commenting on the problem I’m having, should I assume that everyone that has used a Tazer to re-set their tire size to correct their speedometer and odometer calibration due to running oversized tires, was successful in doing so? If so, did you confirm that the changes you made were accurate by checking your Jeep speedometer with a GPS speedometer?

 

[beaups]

Since no one is responding or commenting on the problem I’m having, should I assume that everyone that has used a Tazer to re-set their tire size to correct their speedometer and odometer calibration due to running oversized tires, was successful in doing so? If so, did you confirm that the changes you made were accurate by checking your Jeep speedometer with a GPS speedometer?

Yes and yes.

 

[BLACKMOAB]

I got taller tires by 2”. I’ve increased (and successfully saved) an increased size 6 times in increments and according to GPS it’s not changing the speed on my speedometer - GPS shows 72 mph when speedometer shows 70 mph. I increased the tire size to over 2” taller than what they are with no change to speedometer. The size changes are saving and I’m doing a full reboot after every increase and then making a highway run to check. What could be wrong? I’ve emailed Z Automotive but they probably won’t answer me until Monday.

@joe@zauto I sent an email to Ian but have yet to get a response as maybe you don’t offer tech support on weekends. If you do I would really appreciate your input as resetting my tire size to properly calibrate my speedometer and odometer was really the only reason I purchased a Tazer Lite and I don’t have time to mess with it M-F. Thanks!

 

[Maller]

What tires are you running? Brand and size. What size are you setting in Tazer?

 

[Jason Oliver]

It was exactly the same - speedometer read 70 and GPS read 72.

Then I would suggest that the tazer has done what it was designed to do: your speedometer reads just like it did before the tire change.

If your goal is to match the gps programs, you could try lying to the program about the size of your tires - experiment with it - until you match the gps.

 

[Rudolph Hart]

My apologies if the OP already knows this but the value you put into the Tazer needs to match the true diameter of the loaded tyre on the vehicle. Firstly because tyres aren’t necessarily manufactured accurately to the size the makers state and secondly because the height of the tyre is reduced under load. To get an accurate figure for the Tazer measure the radius from the centre of the wheel to the ground and multiply by two to give the true rolling diameter. Set the Tazer to this size.

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