I'm new to these trucks...and I've just noticed that my speedometer on my daily is quite innacurate. When it says I'm going 60mph my gps shows 55...any ideas?

1986 22rte 4x4

Plate on the door says 225/75 R15
Actual tire size is 235/75 R15

This should make the speedo a tiny bit out the OPPOSITE way!

That's about a 10 percent difference!

 

a bigger tire would actually cause the speedo to read low not high.

If you notice here http://www.miata.net/garage/tirecalc.html with a 235/75 R15 tire on a 225/75 r15 stock sized truck: When your speedo says 60 MPH your real speed should be 61.3 MPH a 2.1% difference.

Sorry to make your problem seem worse, but......

 

I was suprised to find that with 35's on my v6 4runner with 4.56's(stock) I am only off by about 2 mph by GPS at 70....

 

Might be that someone has swapped gearing in your axles at some point, perhaps for larger tires. Now with ~stock size tires, your speedo is off. You could check the axle axle gearing (should be 4.10 for a 5-speed):
- http://www.4crawler.com/4x4/4R_TechI...oDetermination

 

your Toyota is just trying to save you from speeding tickets by showing a higher speed

 

is a 22r/3vz toyota truck even capable of speeding??

 

That's what I was saying when I said it should be out the OPPOSITE way

 

Thanks ill have to check that. Its supposed to have 4.10 gears in it according to the axle code....what should I be revving at when driving at say 50mph in 4th gear(1:1 ratio) with stock sized tires? Lol probably not many guys out there with 4.10s and stock sized tires who can help me out lol.

Not very likely that there could be something wrong with the speedo cable or something?

 

turn the tires by hand and count how many times the driveshaft turns. or vice versa, turn the driveshaft by hand and count how many turns the tire makes.

 

Not really but I know for a fact that it'll almost outrun a bread truck from a dead stop!

 

maybe with a full load of bread. hahaha.

 

yes and ive had plenty

 

So untill I get the time to jack er up and spin the wheels...

when Im going 50mph(actual) in 4th gear im revving @ 2500rpm

I did 4th as 4th is typically a 1:1 ration in most 5spd transmissions and most of you dont have the tall 5th that i have in my r151f

anyone care to post what theyre revving @

Thanks

 

You can plug in some numbers below and find out what you have in the axles:
- http://www.4crawler.com/4x4/4LoCalc.shtml

 

My speedo is off by exactly 10% and my odometer is off by around 7%. I've calibrated my self that if the runner reads 80, I'm doing over 70 but it looks like 80, which feels like I'm making good progress. And, I have the mpg's of 80mph too!!

 

I have a 86 turbo reg cap 4x4 pickup with the manual r151f.

When I got the truck the speedometer was way off. The truck had 4.10 gears and the stock sized small tires. I switched to 31x10.5 r15 and the speedometer was accurate (checked via gps)

Now I have changed my gears out to 4.56 and the speedo now reads 5-6 miles fast. IE it reads 65 when I'm actually going 60 (checked via gps)

Can you tell which gear the trucks that came with 4.56 gears and 31" tires had?

I think my trucks been messed with before. It had 4.10 gears and the factory sized small tires(as indicated on the door plate) however the speedometer was very inaccurate. When I put the larger 31" tires on the speedometer became accurate(checked via gps) even tho it still had 4.10 gears. Now I have changed the gears to be a factory setup(4.56 with 31x10.5" tires) and the speedo is out again (it reads around 65 when I'm going 60)

What new speedo gear do I need?

All you math wizards I could use some help.

 

nobody?

 

http://www.4lo.com/

Nothing is wack your speedo is off again since you changed the gears.

 

no.

The speedo should read correct. I have a stock setup. i.e. 31" tires and 4.56 gears

the speedo only read correct when I had 31" tires and 4.1 gears...which is not a factory option.

I would like to put it correct, but I don't know which speedo gear to buy.....

Its strange that my truck is like this...unless someone has been in there before and at some point in its life the truck had 31" tires and the owner had the speedo gear corrected.....

 

anybody?