Tire size help!

Hi group!
I have a 1981 CB650 Honda, and having trouble ordering tires. The front
Comstar mag wheel has a 100/90/19 57H, so I ordered a Cheng Shin C6000
Barracuda V 100/90V19 tubeless. That seems to be okay.
The problem arrives because I'm changing the rear spoke to a Comstar
mag, and need a rear tubeless tire for it. The wheel says
MT250X16 and I thought a 130/90 would fit this, but the retailer and
Cheng Shin say it needs a smaller size, such as a 110/80/16 or a
110/70/16. The Dunlop book says what I think my Clymer says, that a
130/90 tubeless rear fits.
Cheng Shin, Dunlop do not make these smaller tires, so is the Cheng
Shin tech guy correct?
I'll never buy a wheel w/o tire again, and probably Bridgestones in the
future, but I have to put something new on. I haven't ridden in 30
years, and going back to the spoke rear is a "NOPE".
Any help is greatly appreciated. Thanks! Paul

 

Google up "tire width equivalent chart" and you'll find that you can
mount a 130 millimeter wide tire on a 2.50, 2.75, or 3.00 rim...

You can mount a 110 or 120 millimeter wide tire on a 2.15, 2.50, or
2.75 rim...

Notice which number is in the middle of the rim width range. A 110 or
120 mm tire is more optimally mounted on a 2.50 wide rim, a 130 mm tire
is more optimally mounted on a 2.75 wide rim...

So, what's going to happen with your 130 mm tire on the 2.50 rim where
the rim is pushing the tire beads slightly closer together? The 130 mm
tire is going to get pushed together and the middle of the tread is
going to rise.

This is called "crowning". When you ride, the tire contact patch will
be smaller that optimal. The 130 mm tire will make the rear end feel
like it's "falling into the corner" as you lean the motorbike over.

When you lean the motorbike over, you'll find you run off the edge of
the tread without ever using up all the tread. And, the "crowned" tire
will wear out rapidly in the center without ever touching the edge to
the pavement.

What a waste of money paid for perfectly good rubber because you put
the tire on the wrong width rim!

But you've already selected the WRONG diameter rear wheel. You've
acquired a 16 inch wheel to go where a 17 inch wheel belongs. Putting a
smaller rear wheel which is also too narrow on the back of your Honda
is going to exaggerate the sensation of falling into the corner.

I know all of this because I've spent about $1000 or more putting wide
tires on rims that were too narrow. It never worked out the way I
expected, but people kept patiently trying to tell me what I was doing
wrong and I just wasn't listening...