best odometer/speedo correction device ?

fasthid · **Posted:** Fri Nov 30, 2007 4:57 pm

It's time for bigger tires on our 4x4 '04 KJ, going to 245/75-16's from 235/70-16's, have an auto trans, 3.73 gears, and we want to keep the odometer accurate, helps following trail maps, and also the speedo too.

anyone successfully corrected their speedo/odo themselves? :?:

q50055 · **Posted:** Fri Nov 30, 2007 6:28 pm

yes I do it myself, with the stock tires I mentally reduce indicated speed by 5% (actually drive 5% faster). The MTRs are pretty accurate. :wink:

fasthid · **Posted:** Fri Nov 30, 2007 6:35 pm

oh, I meant I want a device to install to correct the speedo/odo

FreeJeep · **Posted:** Fri Nov 30, 2007 9:14 pm

Took mine to the dealer and they did if for free. Took 2 mins.

DonC

fasthid · **Posted:** Fri Nov 30, 2007 9:18 pm

wow, for free? any clue as to how they did it?

my dealer took 2 mins to program a spare key for me and after they already got me for $50 for the key, charged me $80 for the 2 minutes, or about $2400 per hour shop rate

myjeepwalks · **Posted:** Fri Nov 30, 2007 10:31 pm

q50055 wrote:

The MTRs are pretty accurate. :wink:

same here, i'm within 1-2 mph

DarbyWalters · **Posted:** Fri Nov 30, 2007 11:05 pm

The odometer has been off since you got your KJ :wink:

ryno · **Posted:** Fri Nov 30, 2007 11:27 pm

My speedometer was off about 2 mph at highway speed with the stock 235/70/R16 tires. After switching to 245/70's, the speedometer is spot on, GPS-proven.

tjkoen01 · **Posted:** Sat Dec 01, 2007 12:29 am

I made the same tire change you did. i bought the jet accuspeed thingy....i haven't gotten it to work yet and I'm not feeling to good about it. before i bought it i took it to my favorite dealer and they were going to charge me $90 so i bought the jet accuspeed.

FreeJeep · **Posted:** Sat Dec 01, 2007 10:06 am

spacomponents wrote:

wow, for free? any clue as to how they did it?

my dealer took 2 mins to program a spare key for me and after they already got me for $50 for the key, charged me $80 for the 2 minutes, or about $2400 per hour shop rate

Was a while ago, but I think I just gave them the actual diameter of the new tires and they hooked it up to a little portable scanner lookin thing and updated the program.

itsajeepthing · **Posted:** Sat Dec 01, 2007 10:11 am

Curious, how accurate are speed indications from GPS?

Eddo · **Joined:** Thu Jul 07, 2005 7:01 pm **Posts:** 1214

itsajeepthing wrote:

Curious, how accurate are speed indications from GPS?

Much more than any mechinal speedometer.

csukoh78 · **Joined:** Thu Mar 08, 2007 10:34 pm **Posts:** 501

current GPS technology can maintain speed and distance to around +/- 0.1mph and +/- 0.5 meters.

LostRenegade · **Posted:** Sat Dec 01, 2007 3:57 pm

The dealer needs to reprogram the tire revolutions to correct the spedo and fuel economy gauges. I had several dealers tell me that it could not be done, several that would charge for a full hour of labor. I finally found one that wasn't sure, but would try it. They charged me for only a 1/4 hour of labor even though it took them a while to figure it out.

I am running 245/75/R16 MTRs and my GPS is about 0.5 to 1 MPH off.

best odometer/speedo correction device ?

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