Speedo recalibrator after larger tires?

Don't know if this applies but I've often just figured it was the same case. I have bmw motorcycles and I assume it is the same for other manufacturers that are intentionally set -2 mph. If I'm showing 60 on the dash I'm only doing 58. I run garmin gps so the speed is always showing on it as well. Pretty sure it's all litigation based like many things in this world.

 

Here’s the video.
https://youtube.com/shorts/t_VzPiGlhHE?si=nN5HkpHtim2GGbmv

 

Enjoy the fact your odometer is slowed down. I run an old Escort 9500ix radar detector and set it to display gps speed.

 

GPS speed is horribly inaccurate and has way too many variables to be used.

 

Horribly inaccurate?
I guess we better notify airliners and such

 

they know. Might want to google that. I’ll give you a hint, there is multiple redundant systems. GPS is one portion of the puzzle.

for the topic at hand, I wonder why gps experts have never vouched for it in court to be admissible as evidence? I give you a heads up on googling this….

https://www.seattletrafficattorneys...ext=Not really.,based on RADAR into evidence.

I happen to work in an industry that relies heavily on gps and what it can do. You will never catch me in a court room prepared to testify to its accuracy.

Weather, windows, where the antenna is mounted and more can affect gps. Gotta remember it’s talking to at minimum 3 of the 38 (well 32 operational, 24 nominal) satellites in low earth orbit.

https://www.faa.gov/about/office_or...units/techops/navservices/gnss/gps/howitworks

 

I don't think anyone's talking about going to court, just getting a good idea how fast you are going. And just out of curiosity, how can your industry rely so heavily on GPS and what it can do if it's so horribly unreliable?

 

My dash cam that I just put in last night tracks speed too. Says it’s like 3 miles over what the odometer says but that can’t be right either …

 

Proof that GPS is horribly unreliable?

You could always fire up Waze and look for a speed trap while traveling at 90mph or so. You can then let the trooper tell you once and for all how far off your speedo is. After that, go to court and blame it on your big tires......

 

Ultimately that is driven by customer demand and desire for tracking. Throw enough zeros behind the check and any industry will build what you want and when you sign the contract the limitations of said product are spelled out.

while unreliable, it is also one of the best options available for tracking vehicles and devices. We routinely see videos of vehicles sitting perfectly still and gps says they are moving, I’ve personally seen upwards of 11 mph when the vehicle and the device is not moving at all. We had one particular customer who showed us multiple gps devices displaying the same behavior after many hours and emails spent with them and them not believing us. A different customer gets zero gps reception at their site from any gps device because of where they are at in the mountains, surrounding vegetation and more. Can’t find the truck on the map and its last known location was near the yard? Check the yard as they say. Sharp increases in speed and decreases are not uncommon either. Going from 30 to 110 back to 30 in 20 feet for instance. I could go on..

which is why stuff like our products or Apple tags also use wifi, cellular, or other means of tracking.

overall, there is not much secrecy behind gps and it’s fairly cheap to build into any product. Mostly open source as well for things like metadata. Everything else is handled practically by the gps chip and antenna. Interpreting the data is the only part left which is also mostly handled.

trying to guesstimate how far the speedo is off and comparing to gps is terrible frame of reference in this case. Math would be a much better answer here. Or if you have access to radar/lidar technology.

technology is inherently unreliable and most technological advancements have serious flaws somewhere along the way the average person will never notice or consider. Whether it’s cellphones (recently taken out by a syntax error, a terrorist attack) energy grids (Texas is killed by both heat and cold?) even videos which are subject to the video sensors interpretation of available light, (ever notice color saturation is off? Artifacts in videos? Or the video is synced with led bulbs?)

only thing more unreliable then technology is the element of human error. Ever read a witness statement and then the video is something completely different?

all I’m advising is don’t count on your gps speed to be accurate either.