For a 19 just get the standerd 20 its the same realy wont make any differance! As for buying stupid priced inner tubes what the point even someone who never pops them has the chance to on any. Tesco and asda's own are great i use them on a stock and there brill. there about 1.50 and who would pay like 8 quid for some maxxie one its the same shit.