Setting tires size on tazer mini (most tires are not true size)

Paulocon

Well-Known Member
First Name
Paulo
Joined
Jul 7, 2020
Messages
83
Reaction score
36
Location
Los angeles
Vehicle(s)
2020 Jeep Wrangler jlur
Hello i have 37 inch km3 but heard they are actually about 36 inches

What is everyone setting for their tires at? True tire size or what it says on the actual tire.

Wondering how i should set my tire size when setting it with the tazer mini





Advertisement

 

Medsker

Well-Known Member
First Name
Jon
Joined
Jan 8, 2019
Messages
135
Reaction score
182
Location
Herriman, Utah
Vehicle(s)
2019 JLUR
Occupation
Retired Engineer
When I set it on my tazer I just kept trying sizes and then checking it against my GPS until I got spot on. I also have 37" KM3's and my final setting was 36.52. That would be a good starting point for you. Good Luck
 
OP

Paulocon

Well-Known Member
First Name
Paulo
Joined
Jul 7, 2020
Messages
83
Reaction score
36
Location
Los angeles
Vehicle(s)
2020 Jeep Wrangler jlur
  • Thread starter
  • Thread Starter
  • #3
When I set it on my tazer I just kept trying sizes and then checking it against my GPS until I got spot on. I also have 37" KM3's and my final setting was 36.52. That would be a good starting point for you. Good Luck
Thank you for you response. What exactly are you checking to get spot on when you say checking it against your GPS? Location?
 

Medsker

Well-Known Member
First Name
Jon
Joined
Jan 8, 2019
Messages
135
Reaction score
182
Location
Herriman, Utah
Vehicle(s)
2019 JLUR
Occupation
Retired Engineer
I had a GPS program on my phone I used. After I was pretty sure it was right I also drove around town and hit all the speed limit signs that have radar speed on them. We have quite a few in my town. These were all reading the same as the GPS and Jeep.
 

aldo98229

Well-Known Member
First Name
Aldo
Joined
Nov 16, 2019
Messages
3,124
Reaction score
6,180
Location
Bellingham, WA
Vehicle(s)
2018 Jeep Wrangler Unlimited Sahara, 2018 Fiat 124 Spider Abarth
Occupation
Market Research
Vehicle Showcase
2

RedundanT

Well-Known Member
Joined
Sep 9, 2020
Messages
475
Reaction score
560
Location
So. Il
Vehicle(s)
2020 JLUR
All of the above. I used a level on top of the tire and tape measure to get an accurate measurement. Took several tries as the stupid Tazer with true tire size gave inaccurate speedo readings. So I input size and drive with the GPS app, then input size and drive some more, till it's spot on now.
 

aldo98229

Well-Known Member
First Name
Aldo
Joined
Nov 16, 2019
Messages
3,124
Reaction score
6,180
Location
Bellingham, WA
Vehicle(s)
2018 Jeep Wrangler Unlimited Sahara, 2018 Fiat 124 Spider Abarth
Occupation
Market Research
Vehicle Showcase
2
All of the above. I used a level on top of the tire and tape measure to get an accurate measurement. Took several tries as the stupid Tazer with true tire size gave inaccurate speedo readings. So I input size and drive with the GPS app, then input size and drive some more, till it's spot on now.
The built-in speedometer calibration itself is off. My Sahara came from the factory with the speedometer reading 1.5 MPH faster than actual speed. It wasn’t until I swapped the OE 32.1-inch Bridgestone Duelers for a set of 33.2-inch KO2s that the speedo reading matched my actual speed.

When I went to recalibrate my speedometer now that I got 35-inch tires, I kept that difference in mind and selected a size 1-inch smaller than measured.

For instance, my 35-inch tires measure 34 inches mounted on the Jeep, so I selected 33 inches on the Tazer menu.

I still have to double check that I got it right...
 

Goin2drt

Well-Known Member
Joined
Oct 25, 2017
Messages
2,095
Reaction score
2,313
Location
Kentucky (formerly Peoples Republik of Kalifornia)
Vehicle(s)
18 Rubicon, 17 Grand Cherokee Trailhawk
Measure the actual tire once mounted. Set the Tazer as close to that. Get out your Waze app and drive steady and see if your Speedo matches the speed on the app. If not adjust up or down until it does. Complete.
 

Friday2322

Well-Known Member
First Name
Shawn
Joined
May 23, 2020
Messages
119
Reaction score
91
Location
Kansas
Vehicle(s)
2018 Jeep JLUR
Thank you for you response. What exactly are you checking to get spot on when you say checking it against your GPS? Location?
Google map, Waze, etc. most of them display your speed via gps. It's a pretty simple process. Good luck
 

oldcjguy

Well-Known Member
First Name
Jim
Joined
Aug 26, 2020
Messages
150
Reaction score
138
Location
Central FL
Vehicle(s)
16 Challenger Hellcat, 19 Challenger Scatpack, 20 JLUR Recon
Occupation
Software Engineer
Most accurate way is to measure the radius from the center of the wheel/axle to the ground with the wheel on the jeep. Then double it for diameter, that gives you an accurate "working" diameter. This accounts for compression of the tire from weight of the vehicle.
 

stylett9

Well-Known Member
First Name
Mike
Joined
May 11, 2020
Messages
224
Reaction score
215
Location
Southern California
Vehicle(s)
FJ80, JLU Rubicon
Occupation
Finance
As someone else mentioned, doing a true tire measurement with tape measure did not give accurate results for me either (others have claimed it gives spot on results). I used a cycling app on my phone called strava which tracks real time movement speed. I then bumped it up against a few radar signs in my town to verify.

Here's some details. I went from stock 285 to 315. the manufacture specs claim I went from a 32.8 to a 34.4. Jeep tuning from the factory had a designated size 32.6 and after tape measure, I was supposed to be 33.8. My speedometer was no where near accurate. After doing test runs with GPS on freeway using cruise control, I believe I've settled somewhere around 34.17, running about 36 psi cold.
 

Spank

Well-Known Member
Joined
Mar 29, 2017
Messages
1,455
Reaction score
2,189
Location
Colorado
Vehicle(s)
2018 Jeep Wrangler Unlimited Rubicon, 2020 Dodge Challenger RT Scat Pack
What pressure are you guys running your KM3s? I'm running 37s as well, but keep them around 30 PSI and they measure barely above 35.5in.
 

Medsker

Well-Known Member
First Name
Jon
Joined
Jan 8, 2019
Messages
135
Reaction score
182
Location
Herriman, Utah
Vehicle(s)
2019 JLUR
Occupation
Retired Engineer
I run mine at 30 psi also. I think people are missing the point of this thread. It doesn't matter their actual size, it matters what you need to input into the tazer. When I set mine at 36.52 it doesn't mean that's how tall they are, it means when I input that size into the tazer the speedometer is correct. There is no way to measure tires to hundreds of an inch accurately anyway. At least not with a tape measure.
 

Spank

Well-Known Member
Joined
Mar 29, 2017
Messages
1,455
Reaction score
2,189
Location
Colorado
Vehicle(s)
2018 Jeep Wrangler Unlimited Rubicon, 2020 Dodge Challenger RT Scat Pack
As someone else mentioned, doing a true tire measurement with tape measure did not give accurate results for me either (others have claimed it gives spot on results). I used a cycling app on my phone called strava which tracks real time movement speed. I then bumped it up against a few radar signs in my town to verify.
That's a Jeep for you. People can have the same vehicle, same specs, and make the same changes and get wildly different results. I've got mine set to 35.5" and it matches radar signs and fuel economy hand-calculations perfectly.

It doesn't matter their actual size, it matters what you need to input into the tazer.
It'll matter to your odometer. Every BFG off-road tire that's been made in the last couple decades has always been at least an inch shorter than its rated size. Jeep takes this into consideration from the factory as well. There's an inch and a half difference between the physical tire size and what's programmed into the computer on Rubicons (they did this on the JK, too). If you're telling your Jeep your tires are taller than what you're physically rotating, you're adding mileage that doesn't exist.
 
Last edited:

Advertisement




Gibson Leatherworks
 



Advertisement
Top