I'm a new owner of a 1999 SLT 1500 Quad cab with 52k miles. I love the truck, and it appears very well taken care of. I have a couple of minor issues, one of which is that the speedo reads a little low. It's got the stock tire size, 225/75R16, so I don't know why this would be. Do they all read incorrectly? Is there a known fix for this?

Do a self Check on the Instrument Cluster

Ignition off hold down the Trip reset button keep holding it and turn the ignition on Check should show up in the digital area of the dash and it will do a self test if your speedo is wrong it will give you an error code
Good Luck

Or you could just be a genius and go and have it recallibrated. Pretty much all cars will be a little off either way.

I did the self check, everything passes.

Part of my question was on recalibration; is that an inexpensive thing to do, and are we talking about computer programming or a physical add-on?

They should be able to do a recalibration just through the computer on that thing, and it won't be expensive...

My truck is a 2wd, and it came with P245/75R/16 tires on it. The sheet said it was supposed to have 225's on it, but under the optional equipment list it said it got 245's. For a time I had 225's on the front, and it looked really good because the truck rode higher in the back...

Your speedo could be off because someone put a different sized tire on it before and had the speedo recalibrated? Just a thought.