Tazer Tire Size Setting

[MichiganMojave]

Does anyone have any hints on how to dial in the tire size setting using the Tazer Mini JL? I'm trying to calibrate the speedo for some 35x12.5.17 BFG KO2 tires on standard Mojave wheels. I measured the tires on the truck and got 33 7/8 inches for the height. I have tried several settings ranging from 33.85 to 34.03 but the speedo always reads 2-3 MPH slow. I'm using an app on my iPhone to measure GPS speed for calibration. The good news is I'm getting really good at updating the tire size on the Tazer but it's getting frustrating.

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[cdyoung9799]

I've used the Superchips FlasCal on my last 3 Jeeps. As much as I try to dial it in, it seems I'm always running 1-2 MPH slower on my speedo. Sounds like the Tazer can dial in the actual measurement even better than the FlashCal though. It's been a while since I set it, but I think I can only go up/down in either 1/2" or 1/4" increments on tire size.

 

[kevman65]

Are you rebooting and doing a sleep after you set the tire size?

 

[MichiganMojave]

Are you rebooting and doing a sleep after you set the tire size?

I’m doing a reboot and two sleep cycles after each change.

 

[Killroy Was Here]

Does anyone have any hints on how to dial in the tire size setting using the Tazer Mini JL? I'm trying to calibrate the speedo for some 35x12.5.17 BFG KO2 tires on standard Mojave wheels. I measured the tires on the truck and got 33 7/8 inches for the height. I have tried several settings ranging from 33.85 to 34.03 but the speedo always reads 2-3 MPH slow. I'm using an app on my iPhone to measure GPS speed for calibration. The good news is I'm getting really good at updating the tire size on the Tazer but it's getting frustrating.

This worked for the 285/75R/17 Toyo AT3's that I put on my Mojave.

With the tires inflated to the PSI you are going to run it at, either remove one of your wheels, or jack it up to take the weight off of it.
Then at the center of the tread, use a tape measure to get the circumference measurement of the tire.
Take that number & divide by Pi (3.14159).
This will give you the true actual diameter of your mounted tire at your preferred PSI.
Now you can adjust the setting with your Tazer to the closest choice on the menu.

In my case the actual tire dia. @ 36PSI is 33.79". So adjusted to the
33.85 menu setting.
Checked at highway speeds (65 & 70MPH) with a gps phone app, it's right on the money.

Hope some of this is a help.

Dave

 

[misplacetexan]

Does anyone have any hints on how to dial in the tire size setting using the Tazer Mini JL? I'm trying to calibrate the speedo for some 35x12.5.17 BFG KO2 tires on standard Mojave wheels. I measured the tires on the truck and got 33 7/8 inches for the height. I have tried several settings ranging from 33.85 to 34.03 but the speedo always reads 2-3 MPH slow. I'm using an app on my iPhone to measure GPS speed for calibration. The good news is I'm getting really good at updating the tire size on the Tazer but it's getting frustrating.

Have you tried setting it 34.5, which is the overall tire diameter according to a few websites (tire size.com). Good luck

 

[ShadowsPapa]

iphone not connected to truck is it? Someone somewhere said that if the phone is plugged into the truck - don't recall the details, but make sure your device you use to get your standard is independent of the truck.

If you change the tire diameter it has to change the speed.

I went by tenths of miles traveled. I figured if the odometer was an exact match to my GPS AND phone as far as miles traveled down to the tenth of a mile after 17 miles, it was good.
I set Trip A on the truck to 0, zeroed my GPS and my phone app, and drove 17 miles. The speedometer speed not only matched but when I parked my truck - all three agreed on miles traveled down to the tenth of a mile.

 

[Thrifty]

I used waze gps Speedo to calibrate mine.. put it where you think it should be.. set your cruse control and see how far your off. Adjust accordingly…

 

[MichiganMojave]

Well, after several more tries I finally got things dialed in, but I had to set the tire size to 34.67. Not sure why it’s so much higher than what I measured but it works. I may try the circumference to diameter conversion just to verify but I’m done messing around with it for now.

 

[steveorama]

I used Jscan for my calibration and their instructions say to measure the tire height while under load and then use the closest 1/4" size under that measurement. I ended up trying the unloaded exact tire size of 33.2" (so I used 33.25) and it came out perfect per the Waze app GPS. So it seems like some folks have had positive results using under, over, or actual size. I'm not sure how any of that makes sense as I would assume the same algorithm is at work here.

 

[AZJT]

Yup - after installing my Tazer, I had to fiddle around with the tire size a handful of times before it finally aligned with the speed I was comparing it to using Waze. Trial and error, basically - hence my advocating that folks spend the money on the Tazer and do it themselves. I can't imagine paying a shop to re-set your tire size and then it's off, and has to be re-set, likely a few times.

 

[scoobycarolanNC]

And ALWAYS round down! If you set the size too big and drive around for a month or two you can end up with hundreds of extra miles on the odometer. Ask me how I know.......

OH, the other thing I thought of while messing with this the other day is measure the tire HOT, not cold. Its kind of ridiculous that we use cold PSI for huge tires. I'm running 37s which are 34psi cold and 38psi warmed up. That amount of pressure threw me off by 1/2".

 

[Josh00333]

Do what Papa said. Set a trip on the truck at zero and start a trip in your gps.

I did mine over a couple actual trips and got dialed in to 99.9% spot on, over 180+ mile measurements.

 

[Kevin_D]

Do what Papa said. Set a trip on the truck at zero and start a trip in your gps.

I did mine over a couple actual trips and got dialed in to 99.9% spot on, over 180+ mile measurements.

And use the Digital speedometer.
The analog (gauge) speedometer reads a bit high.

Kevin

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