Oh, 6″? if you’re an adult running KPV you’re gonna’ want to move to 7.10 rears on 8″ rims. I’d put those R5 on ebay and get a new set of Bridgestone YLC with 7.10 rears and run them at 12 psi.
Gif
The R5 tire is approximately 20 years old. The most direct replacement is the DFS compound.
Nothing made currently is going to match tires that old of design and then material degradation over time.
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