Tyres for a big old Jap custom

[Pernig]

I'm looking for a rear first really as mine is almost on the limit. I have tried Avons which were pretty good, and Cheng Shin/Maxxis which were pretty much the same except for a tendency to twitch a bit in conditions with unfavourable grip and perhaps not as long lasting.

I'm looking at BT45s next as apparently they last bloody ages, so should be worth the extra cost. However I've also heard people say they're not so good on larger/more powerful bikes than say a 500 commuter, but for all I know that could be just because there is better rubber available for these wheel sizes. Anyone had experience in owning these sort of 80s Japanese bikes?
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H100 Breaking for spares