My K1100 is on the bench and undergoing various minor surgeries.  I have bought a five spoke rear wheel from an early K1200 that I wish to fit, but I have a question about tyre width.  The tyre on the wheel at present is a 170 section, but if a 180 would slot in it would expand my choice of tyres.  Has anyone fitted a 180 section tyre to a K1100LT using the K1200 wheel?

Depends, a K1200 5 inch wheel should have a 170, but a K1200 5.5 inch wheel should have a 180.

The rim I have is 5.00" in width; I cannot see that fitting a 180 to it will bring about the end of days, so I am concerned about the clearance between the swinging arm/exhaust if a 180 is fitted on a 5.00" rim.  Anybody been there, done that, and worn out the t-shirt?

A little Googling reveals that a 180 should have something upwards of 5.25", so I might well stay with the 170/60 and try the new Avon Storm 3D-XM.  The other issue is a 180/55 is slightly smaller in overall diameter than the 170/60 and the last thing I wish to do is lower the gearing, even if it is only a tiny bit.

On my K100 16v I have tried a 180 on a 5.5 rim with no success. The wheel would require major shimming to clear the swinging arm. I have just had a 170 fitted to the 5.5 rim but will be unable to test this until late next week. Currently I am running a 160 on a 5.0 rim with great success.

"I cannot see that fitting a 180 to it will bring about the end of days" Did I say that it would? I was telling you about experiences of tyre and wheel sizes on some of the BMWs that I have owned. The R1100S came with both of those wheel sizes and both of those tyre sizes and it is accepted that it is not a good idea to mix them the wrong way.
I won't bother answering any of your posts in the future if you are going to be aggressive.

Bikerboy, you have got hold of the wrong end of the stick.  I was not being aggressive, or trying in any way to disrespect you after you had posted advice.  I apologise for hurting your feelings - that was not my intention.