How accurate is your speedo?

Hi, So I'm getting used to my new 2010 Taco DC 4x4 I just got a couple of weeks ago... I have already received much help in other posts on lift mods and tires... So the past few days i have decided to compare my speedometer with my smartphone GPS speedo app.

I have found that the speedo App consistently shows about 2-3 MPH SLOWER than the trucks speedo.

I dont exactly think anybody is to blame or anything wrong is going on. My truck has the cheapie 245's on and one may think Toyota calibrated the Speedos for the 265's ? And I'm seeing the difference? Makes sense, the smaller 245 will get me going slower in the real-world whilst th ECU thinking its trucking at 60mph, the phone says about 57/58 .

I anticipate that will flip when I put on the 285s later on down the road and the truck will show 2 mph slower then.

Thoughts?

 

265, 245 and 285 are tire width, not height

 

Toyota purposefully made the speedo appear that you are going faster than you really are. this way they can not get sued for tickets, and so on. this was by design. every car i have ever owned has been this way.

 

Nah, the speedo just isn't super accurate (it is still within spec though, so there's nothing actually wrong with it).

My 2010 DC OR with 265/70/16's is off as well. When the speedo is dead on 75 the gps is saying 73.

 

Lol, well, I implied 285/75......

75% of 285 is more than 75% of 245.. thus a higher wall.

Sorry for the confusion.

 

When I had 285/60/18s, the speedo was faster than the GPS. 60 on GPS was like 62/63 on the speedo. After I went to 275/65/18s, speedo is now in sync with GPS at all constant speeds. Tires were 31.5", probably closer to 31" as they were nearing replacement. The new ones are 32". I still think the speedo is reading slower than reality but it now matches the GPS all the time.

 

I wonder if I can use this info to get out of speeding tickets

 

No- Because if they catch you doing 65 in a 55...your speedo was probably showing 68...making it that much worse.

With stock tires you'll always be going slightly slower then the speedo shows....Change tires and all bets are off.

 

The accuracy of the burst rating on his Speedo is way off apparently.

 

Mine, like most other Toyotas I've driven, runs at 103% of the truth. 60 on the gps = 62 displayed, for example. It's a very consistent 3%, too, across five different models now.

 

Funnily enough the OBD-II (via SGII) reading is dead-on accurate with my GPS. (Stock tires and wheels). This tells me they either have a cheap-ass D/A converter running the dial or they have it programmed to be a few percent off on purpose. (It's a percentage because the faster you go, the more the inaccuracy)
It annoys the shit out of me. My previous car(s) never had this, but then again this is my first Yota ...

 

this picture on the main page + thread title threw me off considerably.

but yeah, i also have 33" tires (285/75/16) and i'm also 3 mph under.

 

I don't know if this would work but maybe you can take the dial off and put it back on just slightly higher of a speed so it would match up with the GPS when you are at highway speeds. I know when people replace the LEDs in their dash to different colors some people have messed up the calibration on the dial, but since I haven't done that mod I don't know if this adjustment would be a possibility or if it would be too hard to make that little of an adjustment.

 

Lol. Well played.

 

Yes it did! Perfectly.