Motorcycle tire/tube sizes?

[AZRedhawk44]

I'm getting ready to replace the rear tire on my XR600, going to a Pirelli Scorpion MT.  120/80/18 size.  18" is the rim diameter.  I assume the other two numbers are related to the tire width, and the height of the tire away from the rim.  Not sure which is which.

However, I'd like to replace the tube also, when replacing the tire. 

I want a standard schrader valve.  Doesn't seem anyone calls it that.  There's TR4 and TR6 valves.  What are those and which is a schrader valve?  I just want to be able to pull up to any gas station air pump and go to town.

And it seems that tube sizes don't correlate to tire sizes. 

Amazon keyword search for 18" motorcycle tube yields the following:

http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Dautomotive&field-keywords=18%22+motorcycle+tube

Which one fits an 18" rim running a 120/80 tire and is heavy duty and thorn resistant for desert riding?

I suppose it would probably be best to replace the rim strips also when doing this, since I have no idea what condition those are in.  They're cheap, and wouldn't hurt to have on hand if the strips look worn out or oxidized when I get the tire off.  But those are pretty straightforward in sizing.

[tokugawa]

What is this "tube" you speak of? 
 
 for advice on brand and durability the folks at avr are going to have more suggestions than you ever want to read- probably 10,000 pages....
 
 The numbers are width in mm, , aspect ratio, and diameter in inches. .  120/80-18
 Some tubes are still sold with the inch  rim width and diameter sizing. 4.50 x18

this is not an exact conversion, but the tire and tube company's have charts showing the interchangeability, what tubes will fit which tires.

 

[AZRedhawk44]

So a 120/80-18 tire will need a 4.50 SAE tube?  Since 120mm = 4.5 inches (actually, 4.72)?


Or, because it is a Pirelli Scorpion MT, I need a 5.00 SAE tube?

https://www.denniskirk.com/help_center/tire-sizes.jsp#width_table

Note the width table in the link above suggests the "MT" has meaning.

What is this "tube" you speak of? 
 


 

Don't your DR and BMW bikes have spoked tires?  You'd have to have tubes in those two... cruiser and Kawi aside.

[zahc]

http://www.nuetech.com/reviews.shtml

http://www.tireballs.com/

[tokugawa]

"Don't your DR and BMW bikes have spoked tires?  You'd have to have tubes in those two... cruiser and Kawi aside."
 I have never seen them, therefore they do not exist. Only in the event of a flat can their existence be confirmed.!

 The manufacturer should state what sizes the tube is good for.