Another tire recalibration thread...

[Jackpine]

Either I typed something wrong, or you changed your tires or maybe the "gremlins" altered something.

Anyway, your 35" tires should have a circumference of 2792-2793 mm if there is no weight on them. Once mounted, the effective radius is reduced due to weight by close to 3% in most cases, which would make the circumference about 2709 mm.

Now, the 2569 mm figure you were using is too small, which makes your odometer and speedometer read "low". I calculate it as a 5% error, so inputting 2709 would make the 11.5 mile distance on your GPS look more like 11 (actually, 10.97 miles). So, we're getting there.

Now, there's no way your tires are going to have a circumference of 2841, so I'm convinced you must be using the wrong Gear Ratio (GR) too.

The GR code is under the entry "axle" on the VIN sticker. These are the OEM codes that should apply to your truck:

19 = 3.55 open
H9 = 3.55 LSD
26 = 3.73 open
B6 = 3.73 LSD
27 = 3.31 open
18 = 3.08 open
25 = 4.10 open
B5 = 4.10 LSD

So, if the code is "B6" or "26", and you have not regeared, you have a 3.73 axle. Otherwise, you need to enter the size you really have.

See if this clears things up and get back to us.

Edit: We were typing at the same time. Try the TS of 2709 and the GR of 3.55. I'll bet you are going to be VERY close. The difference between 3.73 and 3.55 is another 5%, which brings the 10.4 odometer distance to 11.44 miles. That's about as close as you can measure with those devices.

- Jack