Why You Need a Speedometer Calibrator After Larger Tires or Gear Changes

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Why You Need a Speedometer Calibrator After Larger Tires or Gear Changes

Larger tires are one of the most common upgrades on Toyota and Lexus off-road vehicles. They improve ground clearance, help off-road, and often make the vehicle look better.

The downside is that your vehicle was calibrated for the factory tire size. Once the tire diameter changes, the speedometer and odometer may no longer be accurate.

That is why we developed the Lutz Auto line of speedometer calibrators.

What Larger Tires Do to Your Speedometer

A larger tire travels farther with each rotation. The vehicle still calculates speed based on the original tire size, so it usually reads a percentage slower than the speed you are actually traveling. That means your speedometer may show 65 mph while your actual speed is significantly higher. The error becomes more noticeable at highway speeds and can easily lead to an accidental speeding ticket.

The odometer is affected too. Since the vehicle thinks each tire rotation covers less distance than it really does, it may record fewer miles than you actually travel.

That can throw off:

• Oil-change intervals

• Tire rotations

• Maintenance schedules

• Trip mileage

• Or any other calculation that relies on distance traveled

Our calibrators correct both the displayed speed and the rate at which the odometer adds mileage.

What about everyone's favorite new mod: Portals?

This becomes even more important on heavily modified trucks. Portal systems such as the 74Weld portals make it possible to run much larger tires than would normally fit with better ground clearance. Even though the portals add gear reduction at the wheels, the vehicle may still need speedometer correction because the factory system is still calculating speed based on its original setup.

How CAN Bus and Speed Sensor Calibrators Work

On newer Toyota and Lexus applications, speed and distance information is sent over the CAN bus, which is the communication network used by the vehicle’s computers.

The Lutz Auto calibrator connects plug-and-play inline with the factory wiring without any permanent modifications and adjusts the speed-related messages before they reach the instrument cluster.

It does not reprogram the factory computers. It simply corrects the information used by the speedometer and odometer while allowing the other CAN bus messages to pass through normally.

Older Toyota and Lexus trucks, Jeep applications, Mitsubishi applications, Mahindra Roxor, and compatible 3-wire speed-sensor vehicles generally work differently. Those vehicles usually use a speed signal from the transmission or transfer case, so our older-style calibrators connect in the same plug-and-play fashion but modify that sensor signal instead of CAN bus messages.

Simple Button Adjustment

We wanted the calibration process to be simple.

There is no laptop software, phone app, programming cable, or complicated chart.

The calibrator uses a small remote with two buttons:

• Press up to increase the displayed speed.

• Press down to decrease it.

• Each press changes the calibration by 0.5%.

• Holding both buttons resets the unit to its original setting.

To calibrate it, compare the dashboard speed with a reliable GPS reading and adjust it until they match. Installation and operating instructions can be found on each product page.

Once it is set, the button remote can be unplugged and stored. The calibrator remembers the setting, even when the vehicle is turned off.

Plug-and-Play and Built for Reliability

Our calibrators are designed for plug-and-play installation using vehicle-specific connectors. There is no cutting, splicing, or soldering into the factory wiring.

Each product page includes downloadable installation instructions for the exact vehicle.

Reliability was one of our main priorities. The CAN bus units include built-in failsafe and bypass capability, so if the calibrator were ever to experience a problem (unlikely), it can bypass itself and allow the original CAN bus connection to continue operating.

We wanted them to feel as dependable as the vehicles they are built for.

The units are designed, prototyped, tested, and many electronics are fully assembled in-house by Lutz Auto. Keeping most of the process under our control allows us to make changes quickly, test the products on real vehicles, and maintain better control over quality.

Why You Want One

An accurate speedometer means you know how fast you are actually driving. You do not have to rely on a phone, memorize a correction percentage, or risk a speeding ticket because the dashboard is reading low.

An accurate odometer also helps you keep up with maintenance and track how far the vehicle has really traveled.

The Lutz Auto speedometer calibrator gives you:

• Ability to correct speedometer readings

• More accurate odometer mileage

• Simple up-and-down adjustment

• Plug-and-play installation

• No permanent vehicle programming

• The ability to recalibrate after future tire changes or other upgrades that affect the speedometer or odometer, like portals, tire changes, or gearing changes

  
  

Whether you have installed slightly larger tires or built a heavily modified truck, the goal is the same: make the factory dashboard display the correct speed and mileage again.

Find the right speedometer calibrator for your vehicle in our Speedometer Calibrators collection, where you can choose the correct product and download vehicle-specific installation instructions.