I recently bought a 16/4 rim to build a rear tire for my 78K. I was wondering if a 150/90 tire is going to require any changes to the rear end to accommodate it. Will the chain clear it? I have been told it may rub the tire and am considering getting offset sprockets. Will this rectify the issue, if it exists? With this size tire, are there any factors that might make me rethink getting a sprocket set that is equivalent to stock? I'm under the impression that a 150/90/16 is relatively the same diameter as a 130/90/17, which is on my bike now. Is that a reasonable assumption? Any thoughts/recommendations on the number of teeth in either front or rear sprocket that I might consider? For Christmas, please don't anybody buy me a can of worms. I've got plenty. Thanks.