I'm looking at a great deal on a new wheel. Almost seems too good to be true. Anyway, here's my question. The new rear wheel I'm looking at is 16 X 3.00. The info on the new wheel says it will fit. How do I know what size is on my 1980 sporty right now? The tire is a Dunlop MT90 B16 74H. I bought my bike this summer and it has a lot of after market stuff. Not sure what is what. Thanks.