I don't know about the Metzler
I have an Avon am23 180x55x18 on the back of my Deuce.
I used the PM rage wheel 18x5.50 and all I did (per PM's advice) was remove a small area about 1/8 inch deep by 1/2 inch long from the lower belt guard right where the widest part of the tire sits.
PM's wheels come with the correct spacers to bolt right up without having to size and cut spacers to fit.
PM has a toll free number
I would call them and ask
what they think about the metzler.
They were very helpful on all my ????
You might have to do some spacing with the metzler.
I haven't put many miles on this tire yet so I can't give a good answer on wear,so far so good.
Let me know what you find out.