#### ubercam

##### Veteran Member

From experience and reading quite a lot about it, not to mention hours of searching on Google, I know the Mk4's have an external 43 tooth ABS tone ring and that on Mk5's it's somehow integrated into the wheel bearing or hub. I can't seem to find any reliable info online on how many pulses/rev it gives off. I've looked at pics of the wheel bearing and it's all smooth, no teeth to speak of except for the splines for the driveshaft (36 teeth if you were wondering).

I just can't figure out how VW comes up with their magic numbers so that I can figure out which number is best suited to my tire size (which btw is 15" European OEM 195/65/15). Just going from memory, I think it's currently coded to 3 (21960). From an online tire size calculator I know 195/65/15's are 634.5mm in diameter, 1993.3mm in circumference and do 502 revs/km.

There has to be some mathematical relationship between the tire's size and these magic numbers so I've tried various things in a spreadsheet and the nearest I can come up with that seems to make sense is actually multiplying the revs/km by 44. It seems to be arbitrary at this point unless that's how many pulses/rev and I've answered my own question without knowing it. If that's the case, my cluster coding should end in 2. Working backwards from the magic numbers, 3 = 21960, if you divide it by the revs/km 502 you end up with 43.75. I'll also concede that perhaps one of the magic numbers isn't a perfect exact match and it's just "close enough" which is fine, but I'd still like to know how much it's off by.

Just for reference, here are the coding digits and associated magic numbers, courtesy of Ross-Tech's wiki.

1 = 22188

2 = 22076

3 = 21960

4 = 21848

5 = 22304

6 = 22420

7 = 22532

Any ideas?

Thanks,

Cam