I have a 97 850 wagon and while doing an alignment I ran out of tow adjustment. Both rear wheels are towed out and the adjustments are at the max. No visible damage or bends. Are there shims available for the rear wheels or does somebody know a secret to get additional range to tow the wheels in?

 

You would have to open the holes up more but not really reccomended.
Usually if you run out of adjustment it means one or both of the arms are bent.
They bend very easy on these cars.