130/90-16 rear tire on a '77 KZ1000A

So, I have searched this topic but can't seem to find any relevant info (maybe I'm not good at searching?).

I need some input from y'all... As background, eons ago, let's say circa 1980, Dennis Kirk was closing out Lester Wheels with fire sale prices (only way I could afford them then) and I picked up a 2.15 x19 front and a 3.00 x 16 rear. Installed them on my Z1-B with normal-for-the-time 3.25 tire in the front and 5.10 tire in the rear. Went on perfectly, like falling off a log, no problems.

Fast forward to now and I'm building my KZ1000A. Located and restored the similar 2.15-19 front and 3.00-16 Lester wheels with Avon Roadrider Mk III tires, 3.25-19 and 130/90-16. But now the rear tire significantly rubs the chain guard.

This surprises me, as swingarm geometry, chain guard, etc are essentially identical from Z's thru KZ1000's (at least thru early '80's), so I did not expect this. Is it that the newer 130/90's are significantly wider in practice than the old 5.10's or what? Am I missing something?

I was looking forward to solving other problems I KNEW would crop up when updating, swapping parts, etc., but this was not something I anticipated.

Thanks in advance!

You need a 120 .

Also keep in mind that a 130 Avon will not measure the same installed width as a 130 from another manufacturer, and may be different from a different line from Avon. Motorcycle tires generally come in 10mm increments, so somewhere between 120 and 140 is 130 territory.

Zed1015 has built a bunch of these old bikes, so I would take his recommendation seriously. 

I am running a 150/70/18 on my 77 kz1000 A, but I had to notch the chain guard for clearance. 

It would be interesting to know what the actual measurements on the Avon and Michelin are.

Thanks uranjjj. I note you have a chrome chain guard, is it LTD or aftermarket?

As for tire sizes, while a 120 might help solve the problem, a 120/90-16 Avon RR is not available. There is a 120/80, but the diameter is then down 1.7" do no-go.

As for dimensions, the Avon specs say something like 136-7 mm and it measures very close to this on the bike. Some manufacturers are good with specs (Avon, Bridgestone, probably others), Michelin not so much at least that I could find for their Road Classics for example.

But the dimensions are part of what puzzles me. The old 5.10 tires (it was a Goodyear in this case) measured right about 129-130 mm. And 7mm less width (or 3.5 mm per side) would not cure this.

Chain guards can be replaced or modified, not the end of the world.

Thanks for the feedback!

The "end width" will depend on sidewall construction from one manufacturer to the other. Your 3.0 rim is bang in the middle of correct rim size for the tyre so I guess the "bulge" determined by the sidewalls is where the difference is coming from. I would re-work the chain guard and call it done


 

Yes, I agree. And yes, no two tires from different manufacturers (or even same manufacturer, different model) will even be the same unless it's completely coincidental.  Thanks again.

Again, I have to chime in only to show appreciation for the knowledge on this site.Ask a question, it's answered with experienced solutions.