We've got a 2000 SLT extended cab, 2WD with the 4.7. The previous owner put 255/70/15 tires on it. First question, is the speedo adjustable through the computer, or do we need to change mechanical parts? Second question. When we go around a corner, we hear what sounds like something is rubbing. A kind of squeaking noise like rubber makes. There is no tire rub. It has the anti spin differential in it. Is this something caused by the tire size, or something else? Had the pinion seal replaced a few years back. It only has 115K on the clock.

 

Speedometer is adjusted using a DRB3 or Snap-On Modus 2500, you have to enter the configuration screen for the ABS system and tell it the number of revolutions per mile. How far off is yours showing?

Is the sound more of a squeak or scrub? One direction or both?

Could be a cab bushing. I have a mechanical locker in mine and the inside tire makes an audible scrub around corners. Bushing is more of a squeak. Could also be sway bar bushings or links.

 

The difference depends on the speed. At 60, it's actually 65. It's less at slower speeds. The squeak occurs regardless of which way I turn. It's definitely a rotational noise from the rear of the truck. Had the U joints checked when the pinion seal was replaced and they are fine. I'm less concerned about the speedo, as I have a GPS that keeps me legal. But the rear end noise bothers me.

 

So about 8% off then. Just need to look up the tire you have on it now, find the spec Revs Per Mile (usually listed on tirerack.com), and get somebody with a DRB3 or MT2500 to program that number in the antilock brake controller. Takes about 10 mins.

If it's quiet while going straight and only makes noise when turning, then it's something in the rear end spider gear assembly or the rear sway bar. If it's rotational, that rules out the sway bar. If you had the pinion seal replaced, a good shop should have said something if the clutches were wore out or the retaining clips were in the bottom of the case (they are common to come out when clutches are worn down).

The quad cabs do have a snubber at the very back of the chassis that can make noise. Your extended cab shouldn't have it. It's a 2" diameter steel-and-rubber bar at the very end of the frame rails, where the bumper attaches.