I covered 65 miles on muddy wet forrest roads on Saturday and drove a further 50 miles home , on Monday cleaned and power washed FL2, covered a few more miles. last night overtaking 4 slower cars on uphill overtaking lane the SD easily reached 70+ when it started to shudder violently. Drove rest of journey at 50 and all OK. Feared the worst, damaged wheel(s) or tyre(s)
Sorted in 30 minutes, removed all wheels and washed all the hardened mud from inside rims. The inner rim is 6" wide and there must have been nearly 1 llb in weight on each rear wheel, fronts were fairly clean. All FL2's (3) Gone
2011 Mercedes C180 CGI Gone
FL2 GS Auto SD with heated leather, factory tints, alloy spare and a few other bits.

I have heard about it before, all that mud unbalanced the wheels Former Mod/Member, with the most post & Chicken George Arch nemesis

I suppose when you consider the small weights that are added when they balance the wheels - it wouldn't take much to change it - and if both front wheels were out it would show up at high speeds. 2002 Honda VFR800
2002 Toyota Celica 140 Silver (mid life crisis - again!)
2007 FL2 GS Manual Army Reconnaissance Green + freel2.com sticker
2004 Toyota Celica 140 Black - Gone
2000 Toyota Celica 140 Silver - Gone
1998 Toyota Celica ST Pearl Green - Gone
1996 Nissan Primera 1.6 - Gone
1994 Rover Montego 1.6 Auto - Gone

think there was a post during the winter re packed snow/ice causing the same problem

Iain

i recall that too  Former Mod/Member, with the most post & Chicken George Arch nemesis

You will experience the same after drive in deep snow. If you have no possibility to leave you car in a garage, so that the snow cannot melt overnight, then in morning you will find lots of ice on the rims and wheels completely unbalanced.

Yep that has happened to me