[letumwork]

My truck is completely stock with Lt 265/75r 17 tires and I think the speedo is reading too fast or in other words I'm going slower than the speedometer says. I don't have a GPS to test it but the few radar trailers I've passed seem to indicate this. I have a 6spd auto with 3.73 gears and stock tires. At 60 mph my tach is reading 1500 rpm. Anybody out there with the same set up that can let me know what rpms they are running at 60 mph and if they know if the speedo is accurate? Thanks!

 

[slagburn]

1500 rpm at 60mph here; the GPS reads a few mph lower at any given speed but it's a POS GPS unit.

 

[Syndrome]

I've got a GPS speedometer and according to it the truck is off a bit, but so are the radar signs. The GPS unit I'm using is Passports 9500 radar detector with GPS speedometer.

 

[sladj]

My truck runs almost 2 mph faster than what I am running and puts almost 2 miles per hundred extra on the odometer and it will get worse as the tires wear down...Dealer said there wasn't anything they could do...

 

[stone88]

Yeah my GPS also reads about 2-3 mph slower then the speedometer says going 80mph

 

[KhakiCummins]

Mine is the same way. I guess when I go to the 285's I wont have to have the speedo recalibrated.

 

[6.7 Renegade]

My (currently) stock 07.5 6.7 Mega Cab is running at 77 mph when the speedo reads 80 mph. I use the GPS right now for accurate speed reading.

 

[sweet03cobra]

yeah, I'm a cop and I had several squad cars clock me and at 60 I'm only running 57-58mph, so basically we are losing our warranties fast and getting even worse mileage than suspected. How can this be fixed?

 

[Compcowboy]

tricks of the trade i guess..........LOL!

They will do just about anything.

 

[6.7L OneTon]

Throw some larger tires on there and don't recal your speedo...then you'll be going faster than indicated speed and putting fewer miles on the speedo.

 

[6.7 Renegade]

Throw some larger tires on there and don't recal your speedo...then you'll be going faster than indicated speed and putting fewer miles on the speedo.

Good idea, what goes around, comes around:thumbsup

 

[sweet03cobra]

yeah, then due to the larger tires, you get even worse fuel mileage right?

 

[jon111]

Ive had our traffic unit clock me with radar and laser. both times when my speedometer says im going 65, radar and laser show 62. so i guess im in the same boat as yall.

 

[ynots57]

yeah, then due to the larger tires, you get even worse fuel mileage right?

large heavy tires that add to unsprung weight wont help mpg. a taller profile tire will act like a higher gear ratio

 

[sweet03cobra]

can't a simple computer adjustment fix this?

 

[Syndrome]

Don't most manufactures make their speedometers read fast? Seems like nearly all cars I've tested then the speedometer reads fast. I think they might do it so they wont have any liability of you speeding because of a bad speedometer reading.

 

[sweet03cobra]

yeah but if we are only going 57 when the speedo reads 60, our warrantys are expiring many thousand miles short. That is BS.

 

[xxbaker]

Guess i'm lucky, mine is off less than one mph at 70. I have checked running two gps at the same time. A garmin and a megellen.

 

[slagburn]

My 00 Chevy is off about the same as the Dodge.

 

[mikebol]

How about you recal your speedo to be way low giving you back some of the warranty time they stole and just using the GPS for a speedo? Leave the stock tires on there for better fuel mileage.

Mike