Needing new tires, but the biggest challenge is finding the right tubes.

Need tube for 90/90/21 front tire and 170/60/17 rear tire.
How do the tire size numbers translate into these numbers.
Trying to buy from this website:
http://tiresunlimited.com/motorcycle_tubes.htm

 

The 90/90 21 would take the third from the bottom on the Standard Tubes chart (275/300-21).
The 170/60 17 would take (I'm guessing) the last one listed for 17" on the Standard Tubes chart (500/530-17). Or the last one listed for the Radial/Motard Tubes (150/160/70R17).

 

Why not just go to your local HD dealer and buy the tubes from them...They had the rims made that your new tires are going on and should know best what to use. You will also need new rim bands and none of those things is worth the worry of not having the right one.

 

I don't put cheap tubes in a quality tire. Buy a good brand name tube.