Automatic Speedometer Calibration after larger tire install?

[Nk235]

So I just had new 35x11.5 R20 Toyo AT3s put on my 2019 2500 Big Horn from the stock 33" Firestones and to my surprise the speedometer was dead on at speeds up to 80mph when checked against 3 different independent gps speedos. I checked and the tire shop did not recalibrate anything. I don't have built in navigation but do plug in my phone and use Android Auto displayed on the screen and use that navigation. Is there a chance the truck automatically recalibrated the speedometer for the larger tires? I was researching tuners and had actually ordered a Hypertech device yesterday thinking the speedometer would be off 4-5mph but was very surprised when I checked it out and saw it was already dead on. Just curious if anyone has some insight.

On a side note I really like the AT3s and the 35x11s fit great with no rubbing what so ever.

Thanks

 

[polcat]

I've heard that when plugging into the truck for Apple Car Play or Android Auto, it uses the trucks speedo and not the phone's GPS.

 

[Greenhills]

Speedometer can be out from factory, maybe you just lucked out and it worked out.

When i went to 35s on my diesel, my speedometer was barely 1 kmph out.

Never adjusted anything.

 

[flan]

From 245’s to 285’s mine was off by 7mph at 50mph I had to adjust it with alfaobd

 

[H3LZSN1P3R]

Toyos are usually small compared to the size labeled so in reality if you measure you most likely never increased much to change the speedo

 

[Nk235]

So you're right the Toyo's are small. I just measured them and from the ground to the top most part of the tire is only 33 3/4"
That is pretty frustrating. I never took an actual measurement the same way with the stock Firestone's on there so have nothing to compare it with. Before they went on I rolled a bare Toyo AT3 tire over and stood it next to the stock Firestone on the truck at that time and the AT3s looked much bigger in comparison. That was before they were mounted, inflated and had the weight of the truck on them though.