Try these for your old ringo fits an approx 50” tube sleeve mine is a rage sport twin set
Looked at black inner tubes as a replacement as I had a seem leak and a few punctures but couldn’t find a replacement, I think they want you to to buy a new set but the outer sleeve is ok and quite expensive for complete replacement
Found these at Costco not for purpose but work a treat and at £25 for two a bargain and good quality a few minor drawbacks valves are not in the correct place for inflation/ deflation and a small seating net which has to be cut out
Not sure the cup holders too useful in this application
https://www.costco.co.uk/Sports-Spas...of-2/p/2000527
