speedo out.

exosteve · 15-02-2013, 09:16

my terrano is relatively new ( to us that is) 12 years old lol.
I found out the speedo is out by 8 mph. 30 is actually 38 confirmed by my sat nav.
would this be due to the tyres? they are 235/17r16
steve

rustic · 15-02-2013, 09:22

Quote:

Originally Posted by exosteve

my terrano is relatively new ( to us that is) 12 years old lol.
I found out the speedo is out by 8 mph. 30 is actually 38 confirmed by my sat nav.
would this be due to the tyres? they are 235/17r16
steve

Could you re quote the tyre size, what does the 17 represent 17% of the width?? I don't think so.

If you measure the circumference, then you can compare.

In fact there are sites that give you this information.

However 8 mph in 30 is huge, you would need bus tyres for that error?

edit...
It's not an import is it, with a label stuck over the dial?
Is the odometer in miles?

R1cho · 15-02-2013, 11:54

Quote:

Originally Posted by rustic

Could you re quote the tyre size, what does the 17 represent 17% of the width?? I don't think so.

i think he means 75

jims-terrano · 15-02-2013, 09:27

Hmm good one but people often compare Sat Nav's to Speedo's which is a pet hate of mine. Normally Speedo's say you are doing 30 but Sat Nav's say 25. Personally I'd rather trust the speedo. Not heard of one reading over and to that extent. What year is your Terrano? I'm sure someone will come back and tell you about tyre/wheel sizes but yes they can cause speedo to read incorrect but unsure to what extent.

Can a garage with MOT Brake test pop it on and test speed against your speedo perhaps?

A friend with another car perhaps run at exactly 30 in front of you perhaps compare?

theron · 15-02-2013, 10:46

Speedo's by law can over-read but they are not allowed to under-read. GPS (sat-nav) speed will be slower to update but will be 100% accurate.

AD Ent · 15-02-2013, 10:59

It's normal.
Police cars have calibrated speedos, T2's don't, GPS is calibrated. Terrano speedo is a joke, of all the cars I've tested a GPS App in, It's by far the worse. Mine is on standard 16" wheels and tyres, 235/70/16. 90=80 80mph=70mph 60mph=53mph Bigger the tyres the better it will be.
'Makeitfit' will be along soon with a cure.....

The Big question is.... Have our T2's done LESS Miles than it shows??????? I'm testing this tomorrow.....

rustic · 15-02-2013, 11:11

Here's one to try...

http://www.alloywheels.com/Tyre_Calculator

Rustic

AD Ent · 15-02-2013, 11:20

This too, from the download links

http://www.kouki.co.uk/utilities/vis...ize-calculator

R1cho · 15-02-2013, 11:52

I run 33's and my speedo according to the street speeds radars, my satnav and a local traffic plod i know is spot on 30mph when the speedo says 30mph, for it to be doing 38 at 30 on standard tyres is an odd one to me

AD Ent · 15-02-2013, 12:23

mine is not far off 38 at 30. I'll check and report back.

AD Ent · 17-02-2013, 20:02

Quote:

Originally Posted by AD Ent

It's normal.
Police cars have calibrated speedos, T2's don't, GPS is calibrated. Terrano speedo is a joke, of all the cars I've tested a GPS App in, It's by far the worse. Mine is on standard 16" wheels and tyres, 235/70/16. 90=80 80mph=70mph 60mph=53mph Bigger the tyres the better it will be.
'Makeitfit' will be along soon with a cure.....

The Big question is.... Have our T2's done LESS Miles than it shows??????? I'm testing this tomorrow.....

right did a steady motorway journey. Google maps had it at 45 miles. I zero`d the trip.. At journeys end it read 49.7miles. Out by 4.7miles on a 45mile journey.

Based on that, our T2's have done 10% less miles than it shows on the clock. This affects MPG calculations too.

Lazy-Ferret · 17-02-2013, 20:26

Quote:

Originally Posted by AD Ent

right did a steady motorway journey. Google maps had it at 45 miles. I zero`d the trip.. At journeys end it read 49.7miles. Out by 4.7miles on a 45mile journey.

Based on that, our T2's have done 10% less miles than it shows on the clock. This affects MPG calculations too.

Good point....

Will have a look at ours next time we do a good run in her.

mr tickle · 18-02-2013, 11:59

Quote:

Originally Posted by Lazy-Ferret

Good point....

Will have a look at ours next time we do a good run in her.

This is a very good point.

I have known that my speedo is out by 11% since the day I bought her. I'm not the only one either.
Its no problem at any speed as I compensate accordingly

Speedo 78 mph = actual 70 (11%)
Speedo 70 mph = actual 63 (11%)
Speedo 33.5 mph = actual 30 (11%)

My bus has done a recorded 105k miles = actual 94.5k

My calculated MPG is 25 around town 28 on a run = actual 22.5mpg and 25

It is worth considering.

bry · 02-06-2013, 00:00

Even if you are doing thirty MPH It still a lot faster than a Landy.LOL

96terrano · 02-06-2013, 00:44

Quote:

Originally Posted by bry

Even if you are doing thirty MPH It still a lot faster than a Landy.LOL

Even a scooter is

15-02-2013, 09:16	#1
exosteve Senior Member Join Date: Dec 2012 Location: stoke on trent Vehicle: 2001 2.7 td lwb terrano Posts: 2,740	speedo out. my terrano is relatively new ( to us that is) 12 years old lol. I found out the speedo is out by 8 mph. 30 is actually 38 confirmed by my sat nav. would this be due to the tyres? they are 235/17r16 steve

15-02-2013, 11:11	#7
rustic Senior Member Join Date: Feb 2007 Location: Staffordshire Vehicle: Maverick Mk I 2.7 TD LWB Posts: 7,825	Here's one to try... http://www.alloywheels.com/Tyre_Calculator Rustic __________________ Ford Maverick GLX 1995 2.7TD LWB in illusion silver, 98k miles. Owned since new, for 22 years. Best car I have ever owned. Just wish I could drive it more.

15-02-2013, 09:27	#4
jims-terrano Senior Member Join Date: Sep 2004 Location: UK Posts: 12,965	Hmm good one but people often compare Sat Nav's to Speedo's which is a pet hate of mine. Normally Speedo's say you are doing 30 but Sat Nav's say 25. Personally I'd rather trust the speedo. Not heard of one reading over and to that extent. What year is your Terrano? I'm sure someone will come back and tell you about tyre/wheel sizes but yes they can cause speedo to read incorrect but unsure to what extent. Can a garage with MOT Brake test pop it on and test speed against your speedo perhaps? A friend with another car perhaps run at exactly 30 in front of you perhaps compare?

15-02-2013, 10:46	#5
theron Member Join Date: Oct 2008 Location: Midlands Posts: 98	Speedo's by law can over-read but they are not allowed to under-read. GPS (sat-nav) speed will be slower to update but will be 100% accurate.

15-02-2013, 10:59	#6
AD Ent Senior Member Join Date: Dec 2011 Location: West Yorkshire Vehicle: Terrano II SE+ 2.7 2000 Posts: 915	It's normal. Police cars have calibrated speedos, T2's don't, GPS is calibrated. Terrano speedo is a joke, of all the cars I've tested a GPS App in, It's by far the worse. Mine is on standard 16" wheels and tyres, 235/70/16. 90=80 80mph=70mph 60mph=53mph Bigger the tyres the better it will be. 'Makeitfit' will be along soon with a cure..... The Big question is.... Have our T2's done LESS Miles than it shows??????? I'm testing this tomorrow.....

15-02-2013, 11:20	#8
AD Ent Senior Member Join Date: Dec 2011 Location: West Yorkshire Vehicle: Terrano II SE+ 2.7 2000 Posts: 915	This too, from the download links http://www.kouki.co.uk/utilities/vis...ize-calculator

15-02-2013, 11:52	#9
R1cho Senior Member Join Date: Aug 2010 Location: Wales Vehicle: 1997 LandCruiser Colorado Posts: 4,201	I run 33's and my speedo according to the street speeds radars, my satnav and a local traffic plod i know is spot on 30mph when the speedo says 30mph, for it to be doing 38 at 30 on standard tyres is an odd one to me

15-02-2013, 12:23	#10
AD Ent Senior Member Join Date: Dec 2011 Location: West Yorkshire Vehicle: Terrano II SE+ 2.7 2000 Posts: 915	mine is not far off 38 at 30. I'll check and report back.

02-06-2013, 00:00	#14
bry Senior Member Join Date: May 2013 Location: South Yorkshire.. Vehicle: Nissan Terrano MK 2 SE Posts: 1,757	Even if you are doing thirty MPH It still a lot faster than a Landy.LOL