Has anyone else addressed this? SR5 with stock tires is consistently 2-3mph faster on the speedometer than GPS. I won't be putting larger tires on. Is there any calibration that can be done?
Sponsored
Sponsored
Speedometer calibration after tire and wheel size change?
- Thread starter Gff313
- Start date
- Watchers 13
- First Name
- JT
- Joined
- Apr 19, 2025
- Threads
- 3
- Messages
- 31
- Reaction score
- 26
- Location
- Canton, MI
- Vehicle(s)
- 2025 Toyota Tacoma Trailhunter, 2015 Jeep Wrangler Rubicon
Vehicle speedometer is not determined using GPS. It's determined using the same sensor used for ABS. The wheel speed sensor informs the ECU how fast each wheel's going at any moment in time.
For me, going from OEM to 34s on Riddick, I noticed a moderate change. Vehicle speed is consistently overstated 2-3 MPH compared to GPS.
There are various sites that discuss this, including Tacoma World, Toyota Parts Center, JD Power, and so on. In one article, it indicated it's a rear wheel that is used.
I have owned many Toyotas and all of them showed that I was going at least 1 mph faster than I actually was. I have heard that Toyota has engineered their vehicles to do this on all of their vehicles. Not sure this is totally true but it has been consistent on my end. I think they are erroring on the safe side so to speak for legal reasons.
In any event, if you are placing larger diameter tires/wheels on you vehicle you may actually be spot on with the MPH after the fact.
All manufacturers always err on the side of caution and conservative readings for legal and liability reasons where mechanical systems are used. Because of this, yes, the factory reads high (overstated speed vs actual) when stock and in fact can become spot on with the larger tires removing the intentional slack from the readings. And then with larger and larger it will continue to deviate past spot-on as would be expected.
Sponsored
