how come, my speedo reads correctly with the 33's? - Ranger-Forums - The Ultimate Ford Ranger Resource


Wheels & Tires Semi-Tech General discussion of wheels and tires for the Ford Ranger.
Sponsored by:
Sponsored by:

Reply
 
LinkBack Thread Tools Search this Thread
  #1  
Old 03-09-2009
Tys 4x4 FTW's Avatar
RF Veteran
Thread Starter
iTrader: (8)
 
Join Date: Jul 2008
Location: Las Vegas, Nevada
Posts: 6,575
how come, my speedo reads correctly with the 33's?

i havent changed the settings in the tuner for 33's. its set for 31's.

but i was driving alongside my friend the other day on the highway, and called him and asked how fast we were going. he said 70. thats what my speedo read.

he was in a stock rav 4.

so what gives? im confused.
Reply With Quote
  #2  
Old 03-09-2009
God,Country,FORD's Avatar
Member
iTrader: (1)
 
Join Date: Nov 2007
Location: Red Oak, IA
Posts: 2,468
dude, same thing with my truck.. i was driving into base and the radar thinger said i was going the exact speed my speedo said.. except i dont have a tuner at all and i have 35's..

i was thinking the exact same thing..
Reply With Quote
  #3  
Old 03-09-2009
0RangerEdge2's Avatar
Member
iTrader: (2)
 
Join Date: Jun 2005
Location: Ohio
Posts: 2,593
I think they're set fast from the factory. That's the only explanation. Well actually no, that radar could've been mis-calibrated or the RAV4 could've had a fast speedometer.

Via GPS, I've checked my speedometer. I had stock 235/75R15 (29") to 31x10.5R15 (31") and I noticed a difference. My speedometer is slow at anything above 35 mph.
Reply With Quote
  #4  
Old 03-09-2009
04blackedge's Avatar
RF Veteran
iTrader: (13)
 
Join Date: Jan 2007
Location: Durham, NC
Posts: 23,426
Yeah mine is off too from 29" to 32"
Reply With Quote
  #5  
Old 03-09-2009
SparkYZ's Avatar
Member
 
Join Date: Nov 2007
Location: Granada Hills, CA
Posts: 679
It's common for stock speedometers to be off by a few mph. They arent calibrated for complete accuracy.
If you ever sit in a cop car, well a crown vic anyways, it will say on the speedo that it's been accurately calibrated.

Get a gps and check it. it may be right at 40mph and 2 off at 60mph...

Who knows...
Reply With Quote
  #6  
Old 03-09-2009
black-n-blue's Avatar
Member
 
Join Date: May 2005
Location: Garner, NC
Posts: 810
Quote:
Originally Posted by SparkYZ View Post
Get a gps and check it. it may be right at 40mph and 2 off at 60mph...

Who knows...
Yeah its hard to say.. i went from stock to 31s to 33s and now i have a tuner with the correct speed. But one thing for sure i've noticed is that the faster you are travelling the more off your speedometer is going to be
Reply With Quote
  #7  
Old 03-09-2009
Ray_Welder's Avatar
Member
 
Join Date: Jan 2008
Location: Zephyrhills, FLorida
Posts: 1,037
In mine, I got slight bigger tires, and now 0-35 is accurate, and anything above is 5 below.
Reply With Quote
  #8  
Old 03-09-2009
IanSouth's Avatar
Member
 
Join Date: Dec 2007
Location: Ann Arbor, MI
Posts: 142
My speedo reads 80 when I'm doing 78, so you bumping up to 33's probably just closed that gap.
Reply With Quote
  #9  
Old 03-09-2009
Tys 4x4 FTW's Avatar
RF Veteran
Thread Starter
iTrader: (8)
 
Join Date: Jul 2008
Location: Las Vegas, Nevada
Posts: 6,575
actually mine did the same with my gps. i always thought the gps was off, but now that i think of it, that wouldnt make sense would it?
Reply With Quote
  #10  
Old 03-09-2009
chainfire's Avatar
Member
iTrader: (1)
 
Join Date: Oct 2007
Location: Mission B.C.
Posts: 3,126
Arn't speedo's allowed to be +/- 5% ?. So who knows, your speedo might have been -5% and now with the 33's it will be correct.

Mine is off from going to 29's to 32's as well.

Quote:
Yeah its hard to say.. i went from stock to 31s to 33s and now i have a tuner with the correct speed. But one thing for sure i've noticed is that the faster you are travelling the more off your speedometer is going to be
The reason it is going to be less accurate at higher speeds, is because it changes by percentage. Hard to explain lol.

Ex: Your speedo reads 100 mph with 29's. Going to 32's it will be about 9% difference. so when it reads 100 mph on your speedo, with the 32's you will be going 109 mph. But when you are going only 50 mph, you will really be going 55-56 mph. Not a huge difference, but something to keep in mind when there are police around.


http://www.1010tires.com/TireSizeCal...?action=submit

Your speedo will read aproximatly 5.003% slower.
Reply With Quote
  #11  
Old 03-09-2009
01 ranger 4x4's Avatar
Member
iTrader: (1)
 
Join Date: Nov 2007
Location: Vacaville, CA
Posts: 1,100
yea when im going 70 according to radar and gps my speedo says 75
hopefully when i step up to 33s it will fix that prob
but yea ive heard that our speedos are calibrated perfect for 32-33s
Reply With Quote
  #12  
Old 03-10-2009
Urandaman's Avatar
Member
 
Join Date: Oct 2006
Location: wher ever uncle sam wants
Posts: 1,193
with my truck, even when i had 4.56s it would read the correct speed at low speeds. up until about 32mph. i was using my GPS for my speed readings
Reply With Quote
  #13  
Old 03-10-2009
Blackonblackfx4's Avatar
Member
iTrader: (1)
 
Join Date: Jan 2009
Location: Edmonton, Alberta
Posts: 914
I had a gps in my white non fx4 ranger and with 245's i was at 100 with my 265's i was around 109
Reply With Quote
  #14  
Old 03-11-2009
PUNKROCKPILOT's Avatar
Member
 
Join Date: Aug 2008
Location: Santa Maria
Posts: 446
ive used the mile markers on the side of the road to figure out my calibration. When it says ive gone 1 mile on the road, my odometer reads that i only went 9/10th of a mile. So im 1/10th of a mile off. So when my speedo reads 50 mph, i do the math and know that im really doing 55 mph. speedo says 70 mph, im really doing 77mph... and so on.

Simple break down for all the math wizzes out there:

1/10th of 50 = 5
50mph + 5 (for correct calibration) = 55mph ( new calibrated speed)

1/10th of 70 = 7
70 + 7 = 77
Reply With Quote
  #15  
Old 03-11-2009
jtslmn720's Avatar
RF Veteran
iTrader: (1)
 
Join Date: Oct 2004
Location: Kent State, Kent Ohio
Posts: 7,367
from 27 to 30 mine is only noticeably off after 50mph
Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Speedo reads high 420stackz General Technical & Electrical 2 01-07-2015 05:40 PM
Torque converter not seating correctly BLCNBLU Drivetrain Tech 0 02-10-2013 08:59 PM
Rocker arm issue. Valve not opening correctly. Popping outta exhaust hard. mlw20lu 8-Cylinder Tech 7 01-16-2012 02:22 PM
speedometer and odometer not reading correctly Saberball General Technical & Electrical 0 06-15-2011 07:16 PM
Will not heat up correctly Advocate General Ford Ranger Discussion 7 12-26-2007 07:25 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -6. The time now is 07:30 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.