Here a good one! Does the odometer read tire rotation?

Babe · 07-10-2007, 05:33 AM

Does the odometer on the 3 read tire rotation or from other source.

cause if so, people with slightly larger wheels are screwing themselves of warranty miles.

remmib · 07-10-2007, 05:53 AM

Quote:

Originally Posted by Babe

cause if so, people with slightly larger wheels are screwing themselves of warranty miles.

Why, with larger wheels you get some "free" miles.

Babe · 07-10-2007, 06:02 AM

Quote:

Originally Posted by remmib

Why, with larger wheels you get some "free" miles.

really, I thought since the the tirerack thingy said if going 60, you speedo says 61

MikeCCrutchfield · 07-10-2007, 06:35 AM

Odometer is based on Number of rotations X estimate known circumference (simplified)
so, for sake of argument, 2 rotations at 2 feet circumference is 4 feet traveled
Now, lets say you upgrade your tires and the circumference is now 2.5 feet
2 rotations at 2.5 feet circumference is 5 feet traveled, but your car still THINKS you traveled 4 feet....
Your speedometer also reads low (or closer to actual now)

PS - TOTALLY made up numbers for easy math and explination

Want to add the Number of rotations above can be calculated by engine rpm and gear ratio, wheel speed sensors, all sorts of stuff...
Don't flame me for trying to explain this simply.

Edit
As LEDZEP points out below, number of rotations would normally be based on sensor in the transmission/drivetrain. I was having a brain fart. But the rest of the above still holds true (and if you really wanted to be accurate, you COULD multiple RPM's and gear ratio to get the exact number of revolutions)

LEDZEP · 07-10-2007, 06:45 AM

Most odometers work from the drive train/transmission.

Babe · 07-10-2007, 07:08 AM

cool...

MikeCCrutchfield · 07-10-2007, 07:44 AM

Quote:

Originally Posted by LEDZEP

Most odometers work from the drive train/transmission.

Yeah, Yeah, I was having one of those brain fart days...at least the rest of my post makes sense

LEDZEP · 07-10-2007, 07:52 AM

Quote:

Originally Posted by Mr Crutch 325i

Yeah, Yeah, I was having one of those brain fart days...at least the rest of my post makes sense

Diameter of the tires/wheels obviously makes a difference too! The odometer is set at the factory based on the diameter of the stock packages, with some degree of tolerance. Changing to larger or smaller diameter packages will certainly throw off the accuracy. It's just that it is not actually measured at the wheel usually, but from the gear box.

MikeCCrutchfield · 07-10-2007, 08:16 AM

Like I said...at least the reast of my post makes sense

montreal_bimmer · 07-10-2007, 09:28 AM

Quote:

Originally Posted by LEDZEP

Most odometers work from the drive train/transmission.

KL2DC · 07-10-2007, 09:52 AM

Quote:

Originally Posted by LEDZEP

Most odometers work from the drive train/transmission.

Nice...an info nugget obviously unbeknown to Ferris Bueller

ENINTY · 07-12-2007, 02:30 PM

Quote:

Originally Posted by Babe

really, I thought since the the tirerack thingy said if going 60, you speedo says 61

That's 1.66% off, or 833 miles at 50,000 miles. Ususally BMW speedos are a bit inaccurate so it all works out in the wash anyway...

HyperM3 · 07-12-2007, 02:37 PM

Quote:

Originally Posted by LEDZEP

Most odometers work from the drive train/transmission.

Yes, and theres typically a plug that if disconnected, does you know what. However you will lose all of your dashboard except for the tach. Dont know why that is.

07-10-2007, 05:33 AM	#1
Babe Test here 41 Rep 374 Posts Drives: 2007 335i Alpine White Join Date: Jun 2007 Location: Ann Arbor iTrader: (0)	Here a good one! Does the odometer read tire rotation? Does the odometer on the 3 read tire rotation or from other source. cause if so, people with slightly larger wheels are screwing themselves of warranty miles.
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07-10-2007, 06:35 AM	#4
MikeCCrutchfield Lieutenant 20 Rep 587 Posts Drives: 2008 135i Vert Join Date: Nov 2006 Location: Chestertown, MD iTrader: (3) Garage List 2008 135i Convertible [0.00] 2007 VW Rabbit [0.00] 2006 VW Jetta TDI [0.00]	Odometer is based on Number of rotations X estimate known circumference (simplified) so, for sake of argument, 2 rotations at 2 feet circumference is 4 feet traveled Now, lets say you upgrade your tires and the circumference is now 2.5 feet 2 rotations at 2.5 feet circumference is 5 feet traveled, but your car still THINKS you traveled 4 feet.... Your speedometer also reads low (or closer to actual now) PS - TOTALLY made up numbers for easy math and explination Want to add the Number of rotations above can be calculated by engine rpm and gear ratio, wheel speed sensors, all sorts of stuff... Don't flame me for trying to explain this simply. Edit As LEDZEP points out below, number of rotations would normally be based on sensor in the transmission/drivetrain. I was having a brain fart. But the rest of the above still holds true (and if you really wanted to be accurate, you COULD multiple RPM's and gear ratio to get the exact number of revolutions) Last edited by MikeCCrutchfield; 07-10-2007 at 08:26 AM..
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07-10-2007, 06:45 AM	#5
LEDZEP Lieutenant General 418 Rep 12,276 Posts Drives: 2009 E70 & 2011 F25 Join Date: Jun 2005 Location: Area 51 iTrader: (0) Garage List 2011 X3 35i M Sport [7.62] 2009 X5 M Sport [0.00] 2007 328xi E90 [0.00] 2006 325xiT E91 [0.00]	Most odometers work from the drive train/transmission. __________________ I think it is bad luck to be superstitious
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07-10-2007, 07:08 AM	#6
Babe Test here 41 Rep 374 Posts Drives: 2007 335i Alpine White Join Date: Jun 2007 Location: Ann Arbor iTrader: (0)	cool...
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07-10-2007, 08:16 AM	#9
MikeCCrutchfield Lieutenant 20 Rep 587 Posts Drives: 2008 135i Vert Join Date: Nov 2006 Location: Chestertown, MD iTrader: (3) Garage List 2008 135i Convertible [0.00] 2007 VW Rabbit [0.00] 2006 VW Jetta TDI [0.00]	Like I said...at least the reast of my post makes sense
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