Predator speedo calibration off 4MPH?!?

[DinoMax]

Local police set up one of those signs that give you a readout of your speed as you go buy. Noticed my speedo was always reading 4MPH Less than readout flashed. Figured they rigged it to get people like me to slow down tongue.gif This was with me adjusting w/ Predator for my 315/75/16's. Had Predator off, and truck reset to stock programming on 2 separate days, one for Predator upgrade, and one for a trip to the dealer, and was STILL getting a 4MPH difference :confused: WTF :confused: It is exactly the same from stock AND w/ the Predator adjustment (both versions, v1.04 & v1.07) Any ideas? Thanks, DinoMax :D :D

[Professor]

Which way it is off? and @ how many mph? I had to set mine (on a gas engine) to an odd tire size. Tri changing it to a 320-325/75-16 or 310-305/75 depending on which way it is off. Borrow a GPS and try to check it at 60-70 mph. With the predator, you can change it to sizes that do not exist to fine tune it.

I was able to get mine within 1 mph @70

[FIRELT]

DinoMax
---------i had to put my 36x14.5x16's at 365x65x16 to get it dead on,mike

[Kennedy]

That is one great thing about the Pred. You can enter sizes that do not exist to fine tune. Keep in mind that the error will NOT be consistent as some speedsare noticeably "off" on the speedo. In other words, perfect at 60 mph will be 1-2 off at 70 mph...

Doesn't matter how accurate the correct entry is (remember tires change diameter with psi and rim width) only that you have the ability to tune it how you like...

[DMAX Daddy]

Rumor has it (those that work in Detroit might know more) tht by 2008 all speeds will be based off GPS, with a backup of some sort.

Gotta love Popular Mechanics!

[1BADDMAX]

My Predator (both 1.04 and 1.07) have been really accurate. I notice my needle reads about .5 mph to 1 mph faster than what the Predator reports in real time data monitoring. I don't expect the needles to be dead accurate. After passing several speed signs it's apparent I'm dead on. I set stock size to 245/75/16 and current size to 255/85/16.

[DinoMax]

My speedo shows 4 MPH slower than the radar sign readout/display. I understand I can play around w/ different sizes to fine tune, but I showed the 4 MPH difference with AND without the recalibration done. Guess I'll just have to get a GPS and play a little. Been wanting one anyway. Thanks for the replies, DinoMax :D :D

[DMAX Daddy]

The problem I had was mine was DEAD PERFECT. Then, it went 4MPH off. No changes were made, same driving conditions and temps and air pressures etc etc etc

I reset it with the same settings (265/75/16), and it was perfect again. Then a week later, it was off again, 4MPH.

It was almost like it was losing its setting on the truck computer. :confused: :confused: :confused:

[RWTD]

Originally posted by DinoMax:
Local police set up one of those signs that give you a readout of your speed as you go buy. Noticed my speedo was always reading 4MPH Less than readout flashed. Figured they rigged it to get people like me to slow down tongue.gif Funny you say that, cause I can't ever get the speed displays to stay caught up with my speed. It's weird, I'll be doing some insane speed purposely while passing by it just to see if it is accurate, and it's always like 5 to 10 slow! Although these are the kind that do not take pictures and ticket you via USPS, even so I'd be in the clear! :D

As everyone else was saying, fine tune using the Predator with the odd-ball tire inputs.

Sincerely...