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Will distance and speed related calculation be correct if you change your wheel size to 20" on M5? If so, is there something you can do recalibrate it? Thank you. :flag:
 

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I imagine it might be out by a few Kilometres - to the tune of 1 or 2km. But I don't think it'd be noticable. This is from my experience with other cars mind you.
 

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If the overall diamiter is the same, using lower profile tires, then it should be the same.

Otherwise I have no idea if you can adjust the readings to accept the change. You are best off asking you local dealership.

But remember that the speed readings in the cars arn't that accurate. Look at the mag listings of reading and true speed they are usually about 5% out.
 

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507bhp said:
Will distance and speed related calculation be correct if you change your wheel size to 20" on M5? If so, is there something you can do recalibrate it? Thank you. :flag:
The OEM drive tires on the M5 are 285/35-19's. This gives a diameter of:

.7 x 285 + 19 x 25.4 = 682.1 mm

If you go to 20" wheels, you will need 295/30-20's with a diameter of:

.6 x 295 + 20 x 25.4 = 685.0 mm

The increase in diameter is less than 3/685 =.44%, so you shouldn't see any appreciable difference in gearing, speed or distance.
 
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