Ok, so my 98 4Runner SR5 came with the big brakes and 16" wheels wrapped with 265/70/16's from the dealer. Ever since I have owned my rig the speedometer has read consistently 2-3 mph under my actual speed. I confirmed this with both stupid roadside radar guns set up by the local PD on a busy highway and then with GPS with the cruise set. When I recently up'd my tire size to 285/75/16's the speedo was right on, again confirmed with radar and GPS. You think this was just the result of a tired speedo after 190k or something else?? Its pretty cool though not having to worry about recalibrating the speedo or gears. Does this tell me anything about my gears btw? Have yet to do the simple task of determining my ratio since the codes on the door and the package the truck finally ended up with tell me nothing. What you guys think?

 

Mine did the same speedo wise. Most automatics came with 4:30 gears.

 

Most vehicles off the assembly line are not precise on the speedometer. A 1-3 MPH variance is normal. anything over that should be recalibrated.

 

Just thought it was weird that its right on now. Was expecting it to go farther below the actual speed of travel.

 

consider yourself lucky, as sometimes it can never "line up" right

I would also be curious to see how much it will change when those tires are worn out

 

My 97 sr5 with 285/75/16 bfg and 4.88 gearing reads 2-3 mph slower than I'm actually doing. Thats based off of my garim c580 portable NAV.