Firstly my big compliments for creating this masterpiece!

I have a small problem though. When on the taxiways my aircraft bounces. From the outside you can see dirt bouncing up behind the wheels as if I'm on a dirt road.
This same problem occurs at Simflyers KPHX and I haven't been able to solve this yet.
I'm using FSG 38m mesh, UT USA patch 2, FSG landclass with UTCITY fix.
All these have a priority below KSEA in the scenery.cfg.
Installed KSEA with the terrain mesh fix.
Tried everything from turning of all landclass and vertex-levels 19, 20 and 21. No difference in taxi behavior though

Have you ever experienced this behavior end do you have a possible solution?
Regards, Haromo