Speedometer Error
#11
Contributors
Join Date: Aug 2005
Location: Austin TX
Posts: 6,554
Likes: 0
Received 0 Likes
on
0 Posts
My Ride: 2014 X5 xDrive 5.0 M Package Carbon Black Metallic/2008 M Roadster Imola Red
![Default](https://5series.net/forums/images/icons/icon1.gif)
Originally Posted by clived' post='331260' date='Sep 5 2006, 03:38 PM
There is no "exact" difference - every time your wheels make a revolution and lose a molecule of rubber, the delta will change ever so slightly.... so unless you're going to have a wheel-rotation based speedo that calibrates itself constantly, forget having it accurate.
Long time.
![Smile](https://5series.net/forums/images/smilies/imported/smile.gif)
#12
Contributors
Join Date: May 2004
Location: Dallas, TX USA
Posts: 4,144
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://5series.net/forums/images/icons/icon1.gif)
Originally Posted by monacobmw' post='331136' date='Sep 5 2006, 02:08 PM
Totally agreed here.
I understand that the 5-Series is about 3-4 mph off actual speed at 60mph. You can check it with GPS.
Has anyone figured out the exact differences?
I understand that the 5-Series is about 3-4 mph off actual speed at 60mph. You can check it with GPS.
Has anyone figured out the exact differences?
#13
Contributors
Join Date: May 2006
Location: Miami, Florida
Posts: 719
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://5series.net/forums/images/icons/icon1.gif)
Originally Posted by Hopco' post='331271' date='Sep 5 2006, 07:03 PM
My '06 530xiT has 18" OEM wheels and 4 x 245/40-18 tires with approximately 7k miles on them.
I recently ran a check vs. a GPS: at 70 MPH - the GPS read 68 MPH - or about 2 mph optimistic.
However, when I check my auto's speed against those 25 . . . MPH speed check radars located by local cops about our towns, my speedometer checks out as a bout 4 MPH fast. Perhaps the local cops tune their radars to read 2 MPH slow???
When we drive from Colorado to Connecticut next week I plan to do a series of speedo vs. GPS checks over a range of speeds (30-to-90 in 10 MPH intervals) and will post same.
I recently ran a check vs. a GPS: at 70 MPH - the GPS read 68 MPH - or about 2 mph optimistic.
![Devil](https://5series.net/forums/images/smilies/imported/devil.gif)
However, when I check my auto's speed against those 25 . . . MPH speed check radars located by local cops about our towns, my speedometer checks out as a bout 4 MPH fast. Perhaps the local cops tune their radars to read 2 MPH slow???
![Unsure](https://5series.net/forums/images/smilies/imported/unsure.gif)
When we drive from Colorado to Connecticut next week I plan to do a series of speedo vs. GPS checks over a range of speeds (30-to-90 in 10 MPH intervals) and will post same.
It is when you change the tires to a larger size that you get the changes to the speedometer (they go the other way) because your computer is set to the OEM tire sizes.
#14
Contributors
Join Date: Aug 2005
Location: Austin TX
Posts: 6,554
Likes: 0
Received 0 Likes
on
0 Posts
My Ride: 2014 X5 xDrive 5.0 M Package Carbon Black Metallic/2008 M Roadster Imola Red
![Default](https://5series.net/forums/images/icons/icon1.gif)
Originally Posted by JDN' post='331274' date='Sep 5 2006, 04:07 PM
Mine checks out 2 mph fast at 60. This does not vary much through 75. Hence with a speed limit of 70, error of 2 mph, and a state law that allows 10% above the posted limit before getting points against the DL, I set the cruise at 78.
#15
Contributors
Join Date: Oct 2004
Location: So Cal, USA
Posts: 14,776
Likes: 0
Received 0 Likes
on
0 Posts
My Ride: 545iSMGSilver GrayAuburn Dakota LeatherLogic 7 Premium SoundSports Package
![Default](https://5series.net/forums/images/icons/icon1.gif)
Yup mines 2 mph off at 70. shows 68 on my Garmin GPS and 70 on the speedo.
I'm going to have to check how accurate Lexus is. MINI was also the same. Shows 70 when GPS shows 68.
I'm going to have to check how accurate Lexus is. MINI was also the same. Shows 70 when GPS shows 68.
#16
Members
Join Date: Feb 2006
Location: Alexandria, VA, USA
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
My Ride: 2007 530i, build 03/06, European delivery 05/05/06, Mystic Blue Metallic, Beige Dakota leather and Poplar Grain wood trim. Options: Sport Package, Active Steering, Park Distance Control, Premium Package, and Cold Weather Package. Upgrades: BMW Ellipsoid (Styling 121) cast alloy wheels, AC Schnitzer Aerodynamics Kit, 3M Clear Bra, and RaceMesh Grill.
![Default](https://5series.net/forums/images/icons/icon1.gif)
More information about wheel and tire sizing may be found here:
http://www.carbibles.com/tyre_bible.html#sizes
http://www.carbibles.com/tyre_bible.html#sizes
Thread
Thread Starter
Forum
Replies
Last Post
Vman33
Complete Car Sales
5
03-14-2022 04:43 AM
bimmerspeed
Frequently Asked Questions
1
09-01-2015 05:09 PM