Basic question? And what manufacturer? What is the tire size and aspect ratio? Have you considered marking the tire and floor and rolling it, and measuring,?

Well, I don't have one. And the answer is as easy as a mark, roll, measure.
I Did focus on the question of
Is this a Basic question? And, brainlocked..
I'm good at that.
Spelling test, seventh grade.
I never got below a ninety, so,,I didn't check my work.

Teacher calls out the word

Shed

And, as I wrote the sh, I was thinking, sardonically, the next word will be Real tough, like It, maybe,,
And, I Wrote It, right after I wrote sh, and turned it in...
Ooppsies,
I explained it, he was cool..but he Did call me, rather urgently, to his desk.

According to the calculator, a 140/80-15 is:

23.8189" tall
5.5118" wide
and has a circumference of 74.8293" (or 6' 2.83")


Manufacturers are not that exact though. You WILL find differences in brands and models from what the calculator says.

I'm curious why you need to know. Are you setting a bicycle speedometer/computer to read correctly?

I'm sure Kris's math is correct, but for giggles, I'll do a roll-out check of both my tires. They're the OEM IRC tires with only 125 miles on them, so should be pretty accurate (heck, they still have most of their "rubber whisker," still).

Have to wait for snow to melt, but will post measurements as soon as I can.

And there's an example of what "should be" and what "is"! IRC manufactures their tires (like everybody else) close to the specs that "should be". No one is ever exact. Chalk it up to manufacturing tolerances. That's why some brands of 140/90-15 fit without rubbing and some rub.  

When I was setting up my Trail Tech Vapor.....I did the tape on the tire trick to establish a rolling distance.  When I then programmed that into the speedometer and started checking mile markers along the highway, I had to make a correction.  The rolling distance at speed and when your weight is on the tire - is not the same as when you are pushing the bike across the garage floor.

If you want to get a bit better accuracy - push the bike for 2,2,4,5 tire rotations....whatever you have room to do in your driveway.

For what you are doing....you might just look at Serowbot's gearing charts and find what you want to know.

5 speed chart:
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1341162964

4 speed chart:
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1341280735