So you just got that new lift kit-wheels-tires combo installed, and boy, does that make the truck look amazing! You threw on the mud-terrains, of course, because you wanted grip in the mucky stuff, the wheels because dang, do they look cool, and the lift because there was no way those fenders were going to tolerate rubbing and stay in one piece.
You’re out on a jaunt to celebrate the ride and feel of your truck, and you hop onto the freeway. Everything is going well, and then, you see it – out of your rearview mirror, a cop car is flashing red and blue and you think, “What the…? I was doing 65!”
The officer sidles up to your window and you learn that judging by his speed gun, you were doing 72 when you’re speedometer was telling you 65. It’s an unfortunate circumstance, but there’s a perfectly reasonable explanation – you upped the size on your tires, and forgot to calibrate your speedometer to correct it.
Enter the Hypertech Speedometer Calibrator (PN 752503). Just as the name describes, its main purpose is to recalibrate the vehicle’s speed sensors to account for a change in tire size, and provide your speedometer with the correct information. We received one to use on our 2017 Ram 2500, and got to see what this device does on a deeper level.
With its compact size and neutral design, the Speedometer Calibrator is simple and unassuming. A two-row, dot-matrix display and four buttons are all that go into the presentation of the device. Along with it are a USB cable and OBD-II cable, facilitating internet updates and communication with the ECU, respectively. Given its simple function, so follows its simple form.
The Speedometer Calibrator also has the ability to read and clear DTC codes, too, making it more than just a one-and-done item. Whenever a vehicle throws a Check Engine Light or other trouble light, the Speedometer Calibrator can come to the rescue and give the user information on what’s wrong.
“The vision behind Hypertech’s Speedometer Calibrator is to correct your speedometer and odometer after replacing the stock wheels and tires, especially after lifting or lowering your vehicle,” said marketing director Jason Sakurai. “While it is a feature incorporated into many of our Power Programmers, some owners only want the ability to correct the speedometer and odometer, and this is what they and other enthusiasts requested.”
The amount of applications that the Speedometer Calibrator can work with is staggering. You can see for yourself by way of the Hypertech catalog as proof, and likely find that your vehicle is covered. As for the range of tires that our Speedometer Calibrator could accommodate, Sakurai said, “This particular calibrator features speedometer and odometer correction for 22.5 to 40-inch tires. It changes the diameter in quarter-inch increments.”
Using The Speedometer Calibrator
Before us was a 2017 Ram 2500 with the 6.7-liter Cummins and six-speed 68RFE automatic. The owner, Jason Snyder, had been bitten by the customization bug and wanted to make his truck his own. To that end, he installed a two-inch Pro Comp leveling kit, and swapped out the original 275x70R18 Firestone Transforce tires for a set of 305x70R18 Dick Cepek Fun Country tires. So too went the wheels, the factory chrome units being switched out for a set of Dick Cepek Torque wheels.
As you no doubt noticed from the above, swapping out the Firestones for the Dick Cepeks resulted in another 30 millimeters of increased tire width. The Fun Countrys also had the same aspect ratio of 70 percent, meaning the sidewall increased by about one inch. Comparing the two tires size to size, they were essentially 33-inch versus 35-inch tires. Just for curiosity’s sake, we used Tiresize.com’s comparison visualizer to see the difference these tires make. The results showed us that the difference in tire size becomes more pronounced the higher one goes in miles-per-hour.
We grabbed the Speedometer Calibrator and followed the instructions, which led us to plugging the device into the OBD-II port. The Speedometer Calibrator quickly booted up, performed a DTC scan, and began scrolling directions for us to follow.
Before long, we had made it to the screen where we were to enter the correct tire size. By default, the system recognized that it was programmed for a 33-inch tire. Using the up directional button, we pressed in increments of .25 inches until we reached 35.00 inches, and then locked it in. The Speedometer Calibrator then checked to see if we wanted to change the axle ratios, another factor that, if changed, would have serious effects on the MPH reading. We kept it where it was and moved on.
After a short while, the Speedometer Calibrator reported that it was done programming to the ECU. We removed the Speedometer Calibrator, and this concluded our operation.
What we learned from using the Speedometer Calibrator is twofold. On the one hand, it showed just how painless and simple it was to change something like the tire size and gear ratios on these newer trucks. Secondly, it would help with monitoring the speed, but also the odometer, too; larger tire sizes travel farther in a revolution than do smaller tires, so leaving this uncorrected would give the truck improper odometer readings as the years wore on, showing lower miles than the truck has actually traveled.
If you’ve just been through the ringer of upgrades on your truck, SUV, or other vehicle, and want to keep your speed and miles in check, then the Hypertech Speedometer Calibrator is for you. Check out more information on Hypertech’s products by visiting its website and Facebook page.