tyre tubes

[pembo6]

OK. Silly question.
I have size 26" 2.1 tyres on my MTB. Schwalbe Rapid Rob & Black Jack.

Do I get tubes size 1.7 - 2.1
or
size 2.1 - 2.6 ???

Apparently he Black Jack tyre is quite large for a 2.1. So I was thinking of getting the 2.1-2.6. But I dont want to get a tube too large.

Is there any benefit of getting one size over the other? Lower tyre pressure?

Thanks for your help.

[ozdavo]

Tubes stretch, get the smaller size, less weight & less chance of pinch when fitting.
FWIW I use 26er tubes on my 29er with no problems.

[pembo6]

Thanks ozdavo. That makes sense.