I just purchased a new 170/60R-17 ME 880 Marathon Touring rear tire and also purchased a new tube.
The tube is a Heavy Duty Inner Tube
Size- 70/100-17
I see on this site stating:
Please Note When placing a heavy duty or ultra heavy duty tube in a tire, it is recommended that you buy a tube one size smaller than the tire size.

I don't know what they mean on what part to be smaller.
Do you think the tube will be OK or should I get a bigger one?
Would you recommend a radial tube for the radial tire?
Thanks

 

Bridgestone Motorcycle Radial Inner Tube 150 160/70R-17
Found this radial tube and purchased it on Ebay.
More money but better made for radials on a spoked wheel.
I guess I'm not the only one not sure on the correct better tube.