To all about to get new tires. I have 255/70/16 Uniroyals Laredo AWP's on my 2000 Tundra and love them, quiet, great ride etc. they are smaller than the stock 265/70/16's that were on it when I bought it. I also have a 2000 4Runner and am looking to change to the same tires, but am interested in if there is a way to recalibrate the speedo to be accurate after the tire change, it is my daily driver an am concerned about the speedo being off. Any assistance would be appreciated.

 

Check out Superlift, they have just what you need.

 

Heres a good article for you.
http://www.4x4wire.com/toyota/tech/tacoma_speedometer/

 

Or, get a phillips screw driver and take you instrument cluster out and remove the clear plastic face. Pop the speedo needle off, then put the cluster back in (minus clear cover and needle) and hook it back up. Now drive down the road following a buddy going a known speed. When you KNOW EXACTLY what speed you're going at (60 is a good one, 1 mile per minute), then set the cruise and let it settle out and get steady. Then simply pop the speedo needle back on (at exactly 60 MPH - or whatever speed you do this at) and drive back home. reassemble everything and you're set.

 

That's basically how I do it....nothing too scientific about it.

 

The thing about that is that It will only read the right speed at 60 mph (or whatever speed you set the needle at). The speedo isn't just off by, say 5 miles an hour, It is off by a ratio. If you go to 31 inch tires from the 235/75's on 15s than the speedo is going to be off by about 10 percent: it will read 40 when you are going 44, 50 at 55, and 60 at 66. So if you set the needle at a certain speed, it will read right at that speed, but it will be even more off at other speeds. It is easier just to say "Well, it's off by about 10 %". And figure it in your head. If you're going to 265/70 16 from 255/60 16, you are going to 30.6 inches from 30.1 inches. That's not quite 2 percent off. I wouldn't worry about it.
-Nathan

 

This is true if you have say 31's and go to 32's, at 15mph you are off by about .4 mph, at 65mph you are off by about 2.1 mph, at 100 you are off by about 3.2 mph......... Well you get the idea