The 130/90-15 is withint 1.7% of the diameter of the stock tire (140/80-15).

It will fit without affecting your gear ratio.

However,  you are giving up 10mm of tread width with that tire. That could lead to handling problems, especially when wet.

A 140/90-15 will fit as well, but is nearly 5% taller than the stock tire (which will affect your final drive ratio)

Additionally, the height can cause clearance issues especially when heavilly loaded.

The bolt heads from my bag supports stick out JUUUST enough.  

Not a problem when I'm solo, but put a passenger on the back and it's GRIIIIIINNNNNNDDDDD.

That's with the shocks as firm as they can go too.

skrapiron -FSO wrote on 12/31/69 at 16:00:09:

Actually you are not giving up 10 mm of tread width -- you are giving up 10 mm of tire width.  Your contact patch will be very close to the same.   Rubber compound differences will give you greater changes in handling than going from a 140/80 to a 130/90 rear tire.

MY next rear will likely be a D404 in 130/90.

My new tire will be a 130 width. And the front will be a 90/90 instead of the stock IRC junk.

Narrower tires will turn slightly better than the stockers. Not overtly noticeable, but the difference will be there.  Plus, my bike is now so narrow that the stock width tires look horrible. And vintage tread patterns are more common in the narrower sizes.

The stock Savage is a retro bike... MY Savage looks like it was built in 1957-59 out of an AJS...
-WD