Nooby innertube question-use a 2.35 tube in a 2.1 tyre?

I'm just swapping the tyres on my Fury for some Panaracer Fire XC Pros - but the tyres on the Fury were 2.35 and the new ones are 2.1. Can I reuse the innertubes? I suspect not but I didn't buy new ones to suit the tyres... Grrrr.
0
Posts
Schwalbe do a tube called the AV13 (Fetching name) that is specified for tyres between 1.5" to 2.5" so the small change you suggest will cause no problems.
He that buys flesh buys many bones.
He that buys eggs buys many shells,
But he that buys good beer buys nothing else.</b></i>
(Unattributed Trad.)