Speedometer Self-Correcting... Am I Crazy?

[Uhasib]

I have a 2021 Ram 2500 Power Wagon. I recently upped to 35-inch tires. I have ordered an AEV Procal Snap before I installed them to set the new tire pressure and tire size.

Am I crazy that my speedometer is still correct when comparing it to a phone app? I have gotten bigger tires before (Jeep, F150, etc) and have had to the speedometer be off so I was expecting it to be off as well.

Or is it not a noticeable difference going from the stock 32.7" to 35" tires?

 

[Trooper]

Measure the actual tire height at your desired ride psi. i have 35" Nitto's but at 45psi they measure around 33". i haveht procal snap also but didnt really need to bother with it for that reason.
pump the 35's up to 60 psi and the it gets much closer to 35" but the ride is harsh

 

[LateToTheParty]

Did you check the stock setup against GPS to see if it was reading faster than you were actually going? The last 5 vehicles I've purchased new were all like that, which meant inflated MPG readings on the dash clusters. My 2020 was off when I took delivery of it, but I knew I'd be quickly moving up in size, so didn't worry about it.

 

[Bearman95]

Disconnect your phone from Bluetooth And do not have your phone connected to the truck anyway whatsoever. I thought my 1500 was correct after increasing tire size. But it wasn’t! After turning Bluetooth off I checked it with Garmin and a phone app and saw that it was about 2 mph off when I increased the tire size. That’s the reason I stayed with the stock size on my 2500. I changed the tires to nitto Ridge grappler stock size. It’s already high enough as it is. And I did not have to worry about buying something to correct the speedometer..