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Tire Size Calibration + P160A Warning
A plain-English guide for planning tire-size changes, avoiding speedometer surprises, and knowing what to do if a P160A or wrench warning appears.
Software-onlyBackup-firstIntermediate
1Best use of this free guide
Use it to understand the behavior change before building a worksheet.
2Confirm first
Confirm your year, trim, engine, drivetrain, adapter, laptop, and backup plan.
3Stop if
FORScan will not connect, voltage is unstable, the module/address does not match your worksheet, or the truck shows warnings.
Customer decision
Should you move forward?
Best use of this free guide
Use it to understand the behavior change before building a worksheet.
Confirm first
Confirm your year, trim, engine, drivetrain, adapter, laptop, and backup plan.
Stop if
FORScan will not connect, voltage is unstable, the module/address does not match your worksheet, or the truck shows warnings.
Plain-English promise
This free lesson is here to help you decide, not pressure you. If the setup, hardware, legality, safety, or compatibility picture is unclear, pause and research before purchasing parts, building a worksheet, or writing values. Never copy values from a free guide, screenshot, forum post, or another truck.
Start here
What this means in plain English
Plan tire calibration as a single-purpose session
Tire-size changes need original backups, speed verification, and a clear stop point if a warning or relearn issue appears.
When tire size changes, the truck may still calculate speed using the old tire information. Tire-size calibration is the process of updating the related value so the speedometer and truck calculations are closer to the real tire size.
Software or hardware?
The coding portion is software-only, but the real-world outcome depends on the actual tire size, calibration target, and whether the truck accepts the relearn process cleanly.
Where compatibility gets tricky
Known community discussion is strongest around 2015-2020 F-150 trucks, with special caution for 2017-2018 P160A relearn reports. Confirm your selected year and visible modules before writing.
Before you build a worksheet
Use this free guide to decide if the job makes sense for your truck. If the required hardware, safety impact, adapter connection, or backup plan is unclear, solve that first instead of building a worksheet and guessing inside FORScan.
Visual learning
Pictures, videos, and quick comparisons
Plan tire calibration as a single-purpose session
Tire-size changes need original backups, speed verification, and a clear stop point if a warning or relearn issue appears.
Fast comparison
Use this table to decide whether to continue reading, prepare more, or stop before changing anything.
Best use
Understand the behavior change before building a worksheet.
Good sign
Your truck details, adapter, laptop, FORScan access, and backup plan are ready.
Stop sign
FORScan will not connect, voltage is unstable, or the module/address does not match.
Worksheet fit
Useful for organizing compatible rows, original values, notes, and checks.
Helpful videos and resources
guide
F-Config
Careful Read, Write, Cycle, Verify Workflow
Follow a repeatable process: read the module, confirm original values, write the worksheet values, cycle ignition, and verify.
Open resource
checklist
F-Config
Backup Your Original Module Values
The most important safety step. Save original module values before changing any as-built data.
Open resource
video
YouTube
Loading Factory As-Built Data
External video covering how factory as-built data can be used when restoring values.
Open videoPrep list
What you need before you start
Windows laptop with FORScan installed
Compatible OBD-II adapter
Original tire size and new tire size measurements
Battery voltage plan
Do this first
Before changing any values
Backup rule
Save the original value before changing a row. Only use rows from your own worksheet for your selected truck. If something feels wrong, restore the last original value first.
- Save the original value from every tire-size row before changing it.
- Write down the tire size currently installed on the truck, not only the size you planned to buy.
- Have a GPS speed check ready so you can compare the truck speed after the change.
- Understand the rollback path before writing anything.
Workflow
Simple way to approach it
- 1
Back up the relevant module data.
- 2
Record the current tire-size-related values.
- 3
Apply only the planned tire-size row.
- 4
Cycle ignition and check for warning lights.
- 5
Complete relearn or rollback steps if the truck reports a fault.
After the change
How to confirm it worked
- No wrench light or persistent DTC remains after the drive cycle.
- Speed reading is reasonably aligned with GPS verification.
- Original values are saved where you can find them later.
Avoid these
Common mistakes and problems
- The speedometer is still off after the new value is written.
- A P160A code or wrench light appears after the change.
- The adapter disconnects before the write is complete.
- Multiple changes were made at once, making it hard to know which value caused the problem.
FORScan notes
- Do not expect one universal tire-size code to work for every F-150.
- If a warning appears after the change, stop and restore the last edited original value first.
- Do not combine tire-size work with unrelated comfort or lighting changes in the same session.
Recovery
Rollback plan
- Restore the last edited original value first.
- Cycle ignition, rescan for codes, and avoid further writes until the truck is stable.
Verified facts
FORScan requires proper adapter access and original backups before module changes.
Forum-reported claims
P160A and relearn behavior are commonly discussed by owners, especially around 2017-2018 trucks.
F-Config assumption
A single-purpose tire-size session is easier to troubleshoot than combining several changes.
Trust and limits
Sources reviewed
FORScan official site
OfficialUsed for general FORScan software, adapter, and license context.
Open sourceFORScan community forum
Community-reportedUsed to compare community-reported module behavior and common troubleshooting patterns.
Open sourceFord owner support
OfficialUsed for owner-facing feature and vehicle operation context.
Open sourceF-Config is independent. These notes do not imply Ford, FORScan, forum, or community endorsement. Do not use F-Config to bypass emissions, theft, restraint, safety, inspection, odometer, VIN, or licensing protections.
Recommended next step
Build the worksheet once your truck details are confirmed.
Once the setup is stable and the truck details are confirmed, the worksheet can organize compatible rows, original-value spaces, notes, and completion checks.
This free guide helps you decide
Use it to understand the job, setup, risk, hardware assumptions, and stop conditions before spending money or writing values.
The worksheet helps you do the job
After you choose your F-150 and compatible mods, the worksheet organizes rows, original-value spaces, notes, and completion checks.
Keep learning
Related free guides
Start here
What Happens After You Buy a Worksheet
See clearly what the worksheet gives you, what it does not do for you, and how to use it before opening FORScan.
Start here
Choosing a FORScan Adapter for an F-150
Understand why the adapter matters, why stable USB is often the safer default for writing values, and what to avoid before buying parts.
Start here
How to Back Up Original Values Before Changing Codes
A simple backup-first guide for recording original module values so you have a rollback path if a change does not behave as expected.
Ready for a truck-specific worksheet?
The free guide helps you understand the work. The worksheet organizes compatible rows, original-value spaces, checks, and notes for your selected F-150.
Free guide boundary
Free lessons teach the decision and setup. The private worksheet is the truck-specific work surface.