solution for increased overall size of wheels

x.zhang · 10-16-2019, 03:56 AM

M5 wheel's overall size is about 3% bigger than them on a regular 5 series, while they have the same space for wheels, that makes wheels on regular 5 series look too small.
Since we can't directly put on bigger tyres that will effect the speedometer, either the diff ratio or some data in one/few of the ECUs must be changed so the speed would match.
in some cars changing the tyre parameters is really simple but i looked up the internet and didn't find anyone has done this on a BMW.
Any input will be appreciated!

wcr3d · 10-16-2019, 09:14 AM

BMW speedometers aren’t exactly accurate to begin with.
To keep you safe they show higher than actual.
There are some threads about coding this out if you search.
I can’t say much about the rest as you don’t give enough detail.

10-16-2019, 03:56 AM	#1
x.zhang New Member 0 Rep 5 Posts Drives: 2011/535i Join Date: Nov 2018 Location: shanghai, china iTrader: (0)	solution for increased overall size of wheels M5 wheel's overall size is about 3% bigger than them on a regular 5 series, while they have the same space for wheels, that makes wheels on regular 5 series look too small. Since we can't directly put on bigger tyres that will effect the speedometer, either the diff ratio or some data in one/few of the ECUs must be changed so the speed would match. in some cars changing the tyre parameters is really simple but i looked up the internet and didn't find anyone has done this on a BMW. Any input will be appreciated!
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10-16-2019, 09:14 AM	#2
wcr3d Captain 461 Rep 659 Posts Drives: 2013 535i XDrive M Sport Join Date: Aug 2012 Location: Indiana iTrader: (0)	BMW speedometers aren’t exactly accurate to begin with. To keep you safe they show higher than actual. There are some threads about coding this out if you search. I can’t say much about the rest as you don’t give enough detail.
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