3rd Gen Toyota Tacoma In-Line Speedometer Calibrator Rough Country & Hypertech
After installing larger tires, your truck will read less mileage on the odometer and slower speed on the speedometer. In order to correct this, you can install an In-Line Speedometer Calibrator. There are a few units out there that will fix this issue.
Many of these also claim to improve efficiency, horsepower and torque on your Tacoma. Depending on the unit you buy, it will allow your Tacoma to gain more power and improve quicker acceleration, or otherwise known as throttle response.
Let’s jump into it.
What does the Speedometer Calibrator Do?
Your vehicle’s ECU is designed and manufactured to track the speed of your vehicle based on a preset stock tire height. When upgrading to larger tires, this calculation becomes incorrect.
That’s probably why you notice that when tracking your MPH on an app like WAZE, your gauge cluster speed and the GPS tracker on your phone for your speed are different.
This can also affect your MPG reads if you’re tracking that as well. This plug-and-play device connects directly to your Tacoma’s “Diagnostic Link Connector Port,” and after installation, your speedometer will read correctly again!
The calibrator doesn’t just correct your speed it also updates your vehicle’s ECM, so that your shift points are accurate as well with the larger tire sizes and correct speed accounted for. If you decide to go back to a smaller tire size, then the process can be easily reversed.
What’s the Difference Between the Two Products? Rough Country vs Hypertech?
Both products look exactly the same, the unit plus the harness they both come in. Rough Country Comes in red and Hypertech comes in black. This will not affect anything since the unit is tucked away behind the gauge cluster. The major difference will be in your wallet!
The Rough Country comes in at $139.99 and the Hypertech Version comes in at $229.00 to $260.00 in brand new condition depending on where you’re buying it. They are the exact same unit, just branded and boxed differently. I can attest to this because I personally own the Rough Country Version, but I went on the Hypertech’s site to download their software.
Step 1. Download Hypertech’s Tuner Update App Software on your PC Laptop
Depending on the type of operating system you are using on your personal laptop, it may or may not download, some versions of Windows and different versions of Mac must be figured out before the download. If if you’re having trouble, then call the manufacturer to see if they can walk you through it or try a different computer if that’s the issue.
Step 2. Select Vehicle Model, Trim & Old (Stock) Tire Size
When you’re on the programmer screen (whatever the current version is), find where to select your vehicle model and trim. Select “ Tires are not Stock” and then proceed through the menu.
Your Old (stock) tire size should be on the lower B Column on the driver’s side. Input that size (whether metric or standard) into the “Old Tire Size”. Then do the same thing with your new tire size on the input to the right.
Note: It is important to remember not to program your stock or new Gear Ration because this does not affect the MPH read; this will actually cause the calibrator to be thrown off.
Step 3. Enter In Your New Tire Size, That’s It!
Once you have entered the tire size difference and also program the unit, then you’ll be done!
Pro tip: Leave USB Cable Attached To Calibrator For Easy Access To Gauge Cluster. When plugging the unit into the back of the gauge cluster, I recommend that you leave the USB cable attached to the calibrator and leave it hanging (tuck it in nicely!) so that it comes out close to where your TPMS reset button goes. This allows you to just plug in the computer if you change tire sizes versus having to remove your whole gauge cluster again to access the unit. Tuck it in with a zip tie and make sure you have enough slack to reach your computer.
This unit was extremely easy to install; here is a video by Alex Caffentsiz outlining his install with the Hypertech Version.
I was extremely happy with this modification. It gave me peace of mind that, at all speeds, my speedometer was reading the correct MPH. You can also test this by downloading a speedometer app on your phone or using the Waze GPS app as mentioned above.
This corrects the discrepancy you get when upgrading to small tires and also closely dials in on what you are really getting for your MPGs. The only thing that the calibrator does not fix, however, is the “total mileage” that your tank reads when you fill up with a full tank of gas. This will still read incorrectly depending on your “non-stock tire size” and “non-stock weight” your truck modifications added to your stock curb weight. I would definitely recommend this to anyone going 33’s and above on their Tacomas.