Interesting Speed / Larger Tire Observation

[troutspinner]

Last year when I put my larger tires on, I measured the Speedo vs GPS on the phone. Speedo showed 59, GPS was 60. I called it good enough, I would just adjust cruise control down a mile or two from what I felt was a safe “Let’s not get pulled over” speed. Knock on wood, no R&B’s in the Rearview to date.

Today coming back from salmon fishing (4 hour ride) my buddy took over CarPlay and used Waze. Waze shows actual speed and it was DOBA (dead on balls accurate - my cousin Vinny )from 0 to where I topped out.

So...do these Rams actually self adjust? Do they use GPS for speed? Does Waze get the speed from the vehicle rather than GPS?

I just thought it was interesting and thought I’d share as I’ve seen many posts about programmers. On the down side, it’s means my MPG is actually as bad as it shows.

 

[AndreiV]

Last year when I put my larger tires on, I measured the Speedo vs GPS on the phone. Speedo showed 59, GPS was 60. I called it good enough, I would just adjust cruise control down a mile or two from what I felt was a safe “Let’s not get pulled over” speed. Knock on wood, no R&B’s in the Rearview to date.

Today coming back from salmon fishing (4 hour ride) my buddy took over CarPlay and used Waze. Waze shows actual speed and it was DOBA (dead on balls accurate - my cousin Vinny )from 0 to where I topped out.

So...do these Rams actually self adjust? Do they use GPS for speed? Does Waze get the speed from the vehicle rather than GPS?

I just thought it was interesting and thought I’d share as I’ve seen many posts about programmers. On the down side, it’s means my MPG is actually as bad as it shows.

After a year of driving you lost some thread life and overall wheel diameter, so with time there is less and less difference in speed due to larger tires.

 

[Rob5589]

1 mph is too small to really say one is more accurate than the other. With a larger diameter tire, the speedo should have been reading slower than the gps.