Tire size coding · mobile service
Bigger tires? I'll recalibrate the truck for the size you're actually running
Price
$45
$45 on its own · $79 with a full-system scan
Mobile service
I come to you
Serving Chattanooga and surrounding areas
You lifted the truck and put bigger tires on it. It looks right. Then you noticed the speedometer reads low, the odometer is quietly wrong, and the transmission shifts like it's been given bad information.
Nothing is broken. The vehicle is still calculating as if the original tires were on it.
What actually changed
Tire size changes rolling circumference — how far the truck travels for one full turn of the wheel. A taller tire covers more ground per revolution.
Your vehicle doesn't measure speed with a cable any more. It calculates speed from wheel-speed data, and it was configured for the tire size it left the factory with. Put a bigger tire on it and that calculation is wrong: the truck thinks it's going slower than it is, and every speed-based function built on that number is off by the same percentage — speedometer, odometer, and the speed references used for shift scheduling and other vehicle logic.
Your ABS and TPMS systems can be affected too. Some vehicles need tire size configured in their other modules, not just the cluster.
The fix is a configuration change — no hardware
There's no module to swap, no calibrator to wire in, nothing to zip-tie under the dash. On supported vehicles the correct tire size is written into the vehicle's own configuration through the OBD port.
That's the kind of coding I do every day:
- RAM and Jeep — through AlfaOBD, connected to the vehicle's modules
- Ford — through FORScan, the Ford-specific software
- European vehicles — through the correct software for their systems
Once the tire size is set correctly, the vehicle calculates from the right diameter, and the speedometer, odometer and speed-based logic follow. I verify it while I'm standing at your truck rather than telling you it's done and driving off.
Two ways to buy it
$45 — Tire Size Recalibration. The configuration change on its own: the correct tire size set in the module, verified.
$79 — Tire Size + Full-System Scan. The recalibration plus a full-system diagnostic of every accessible module in your vehicle: engine, transmission, ABS, airbag, body, cluster, HVAC, TPMS. You get the digital health report with the codes found, what they mean, and recommended next steps.
If you've just done a lift, spacers, wheels and tires, the bundle is the sensible version. Suspension and wheel work has a habit of leaving something switched off, unplugged or reporting a fault — and a full scan after the build tells you what your truck is saying before it becomes a problem on the road. Same visit, both jobs, $79.
Tell me this when you get in touch
- Your year, make and model
- The tire size you're running now, and the stock size if you know it
- Whether anything else changed with the build — lift height, gear ratio, wheels
- Whether your speedometer is reading high or low, if you've measured it
With that I can tell you whether your vehicle supports the change, which module it lives in, and what it costs — before you book.
Compatibility is verified first
Supported years and procedures vary by year, make and model — some vehicles accept the tire-size configuration through their modules, others don't, and the module it lives in differs between platforms. Compatibility varies by year, make and model, and I verify yours before you spend anything. If your vehicle can't take the change, I'll tell you that before you spend a dollar.
Where to go next
I verify compatibility and give you the price before we schedule — if I can't deliver, you don't pay.
Prices are starting prices, not guarantees. Final pricing can depend on the vehicle, location and work involved; a travel fee applies beyond 10 miles. Compatibility varies by year, make and model and is verified before any appointment. This is an electronic diagnostics, coding and reset service — not mechanical repair. No dealership or manufacturer affiliation.