86 87 4Runners

Need any body that can help with my speedometer issue. going down the road the other day i noticed i was speeding pretty bad but my speedo was telling me i wasnt. Used my gps to tell me how fast im going now and its off by 20. Sometimes it just fixes itself. Havent had a problem before till now. just want to know if anyone knows what to do to fix this? yes i do have bigger than stock tires. they are 265/75/15 and that size has been ran on there for probably about all its life. The only time it would not be right is about 55-60 and it starts being 5 over.

millball

If the issue is intermittant, the fault is likely in the speedo head itself.

There can be no fix but specialist repair and calibration.

RAD4Runner

Speaking of a fix...
With many of us changing gearing / Wheel sizes and trucks getting old to find replacement parts. I wonder if anyone had used a GPS/Phone app as substitute for the mechanical Speedo. Something that can be ran whenever truck is driven.

scope103

Not with an automatic.

86 87 4Runners

i am using my gps all the time now just so i know. I might be running it this was for a while. My buddy done the same thing on a car and truck of his at one point im pretty sure. but most of us with these old toyotas they are manuals. But i think you should be able to right? When youre using the gps itll tell your speed by how fast its going period, and it shouldnt be able to tell if you have bigger tires or lift etc.