W220 air matic issue over 65mph

[Dragonml]

Hi all.
Finally after working on 2003 w220 cdi lwb for 4 5 months i got it on the road and took it for spray job.
I have upgraded factory staggered 18s rims for 18s of 2012 w221.
Standard w220 staggered set up had 245/45/18 fronts and 265/40/18 rears.
New wheels from w221 are 18s 8.5j all around and 255/45/18 tyres.
New tyres are 68.65mm in diameter and old set up is 67.77mm diameter according to my calculation.
Car drove fine with my test drives aroing streets etc. Yesterday i took the car to body spray shop and first time took it up to legal speed.
Ones i got to approx 65mph msg got displayed airmatic fault,in white with arrow pointing up on the screen?
Car never lost any power and kept driving fine.
I dropped the car at body shop and left it there.
Hopefully i will have it back in week time,but i would like to start thinking where do i start with this fault?
Car drove fine without any airmatic issues when i got it, i drove it 200miles back home and done lot of work underneath the car. Rear subframe re bushed ,shock too,sandblasted and painted and protected. All back together drove fine, new rims fitted and airmatic issue popped up only when speed was over 60mph.
Can anyone give me any tips ,advices .
Difference with old and new tyres is less that 10mm,can this play such a big part.
Thank you

 

[Atavus]

I expect it’s trying to lower itself at around that speed and that triggers the error. There are web pages with troubleshooting steps that you could look at. Like this - http://www.mercedesmedic.com/air-suspension-troubleshooting-airmatic-visit-workshop/

 

[Dragonml]

Thank you.
I have that link saved.
To add to my post above .
Car don't drop on any corners,i lifted it to high setting and took measurements and after 20 days i got back from holiday and it didn't drop a single mm.
I do have a issue with rear drives side that is driving me mad (uk drives side) its 15mm lower that passenger side.
I swapped the shocks around when i had subframe off and its still the same,so this eliminated airmatic strut issue i swaped valve block for good working one still same so i think issue is within software setting .
I will have to wait until i get it back and start checking everything.
Thank you for your help

 

[Atavus]

You certainly don’t have a leak, which is good. There are height sensors by the looks of things and they can fail.

 

[Craiglxviii]

If you’ve got 68mm diameter wheels, how is the ride over our potholed roads?

 

[Atavus]

I’d decided not to go there

They were pretty good when I had a skateboard.