Speedometer Calibrator
See exactly how far off your speedometer is after bigger tires, and get the right fix.
Going from 31\" to 35\" tires creates a 12.9% speedometer error, your speedo reads 70 mph when you're actually doing 79. This affects shift points, ABS, and odometer accuracy. A performance tuner ($300–$600) is the easiest fix.
HOW IT WORKS
Enter Tire Sizes
Input your stock and new tire diameters using sliders or exact sizes
See the Error
View speedometer error, actual speed at 70 mph, and annual odometer drift
Get the Fix
Compare tuner, calibrator, and dealer reflash options for your vehicle
Enter Your Tire Sizes
Your speedometer reads slow, you're going faster than indicated
Speedo says 30 mph
32.8 mph actual
Speedo says 70 mph
76.6 mph actual
Odometer error/year
1286 miles lost
How to Fix It
Three ways to correct a 9.4% speedometer error
Performance Tuner
Pros
- Corrects ALL systems (ABS, TC, trans)
- Performance gains included
- Adjustable for future tire changes
Cons
- Higher cost
- Potential warranty concerns
- Vehicle-specific
Best for: Modern trucks (2015+) wanting performance + correction
Inline Calibrator
Pros
- Low cost
- No ECU modification
- Transferable between vehicles
Cons
- Only fixes speedo/odo
- May not correct ABS/TC
- Wiring splice required
Best for: Older vehicles or budget-focused builds
Dealer Reflash
Pros
- 100% warranty-safe
- Corrects all systems
- No hardware needed
Cons
- Not all dealers offer it
- Limited tire size options
- May refuse modified vehicles
Best for: Warranty-critical or factory-option tire sizes
At 9.4% error, these systems are affected:
RELATED CONTENT
Speedometer Calibration Guide
In-depth guide covering tuners, calibrators, and dealer reflash options.
Re-Gearing 101
When and why you need new gears after bigger tires.
Tire Size & MPG Impact
How bigger tires affect fuel economy and what to expect.
33s, 35s, or 37s, Everything Changes
The real-world impact of upsizing tires on every system.