Speedometer Correction Table Generator
Generate a printable speedometer correction table for your tires: indicated vs actual speed in mph and km/h at every 10 mph step.
Tabulate indicated and estimated actual speeds.
Speedometer Correction Table Generator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Speedometer Correction Table Generator Works?
The Speedometer Correction Table Generator works by applying one correction factor to a range of indicated speeds and laying the results out as a printable table. The tool uses 4 steps.
Enter both sizes
Type the calibrated and fitted sizes, or enter a correction factor directly.
Choose the range
Pick a start speed, end speed and step, for example 20 to 90 mph in 10 mph steps.
Choose units
Select mph, km/h or both columns.
Print or export
The generator builds the table for printing, saving as PDF or copying into a spreadsheet.
Speedometer Correction Table Generator Formula
The Speedometer Correction Table Generator applies V_actual = V_indicated × CF to every row from V_start to V_end in steps of Δ.
V_i(k) = V_start + k × ΔV_a(k) = V_i(k) × CFn = (V_end − V_start) ÷ Δ + 1- CF
- Correction factor OD_new ÷ OD_cal
- Δ
- Step size (mph or km/h)
- k
- Row index 0, 1, 2 …
Worked example
For 285/75 R17 tires on a truck calibrated for 265/70 R17, CF = 1.0704. A 20–90 mph table in 10 mph steps has 8 rows, and the 90 mph row shows 96.3 mph actual.
Speedometer Correction Table Generator Conversion Table
The Speedometer Correction Table Generator conversion table is a sample 8-row output for a truck calibrated for 265/70 R17 and fitted with 285/75 R17 tires.
| Indicated (mph) | Actual (mph) | Indicated (km/h) | Actual (km/h) | Gap |
|---|---|---|---|---|
| 20 mph | 21.4 mph | 32 km/h | 34.5 km/h | +1.4 mph |
| 30 mph | 32.1 mph | 48 km/h | 51.7 km/h | +2.1 mph |
| 40 mph | 42.8 mph | 64 km/h | 68.9 km/h | +2.8 mph |
| 50 mph | 53.5 mph | 80 km/h | 86.1 km/h | +3.5 mph |
| 60 mph | 64.2 mph | 97 km/h | 103.4 km/h | +4.2 mph |
| 70 mph | 74.9 mph | 113 km/h | 120.6 km/h | +4.9 mph |
| 80 mph | 85.6 mph | 129 km/h | 137.8 km/h | +5.6 mph |
| 90 mph | 96.3 mph | 145 km/h | 155.0 km/h | +6.3 mph |
What is Speedometer Correction Table Generator?
A Speedometer Correction Table Generator is a tool that builds a full chart of indicated and actual speeds for one tire setup. The chart works as a dashboard reference card or a record for inspection.
A single correction factor shows the error in percent. A correction table shows the error in real speed units at every speed the driver uses.
The generator supports metric and imperial columns side by side for drivers crossing between countries.
What are the uses of Speedometer Correction Table Generator?
There are 4 main uses of the Speedometer Correction Table Generator, including dashboard cards and inspection paperwork.
Dashboard cards
Print a small card for the sun visor or glovebox.
Inspection paperwork
Attach a correction chart to modification records.
Cross-border driving
Show mph and km/h together.
Before-and-after records
Compare the chart before and after recalibration.
Related Speedometer & Distance Tools
View All 134 Subtools →Estimate speed changes after tire resizing.
Estimate road speed from indicated speed.
Estimate displayed speed at a given road speed.
Calculate a tire-size correction multiplier.
Estimate distance recording differences.
Adjust indicated distance for tire changes.