Plastic rims and brake pads

I have a pair of 16″ plastic wheels on a scooter-bike that is slowly being refurbished. The brakes have been tweaked to remove slop, and I have fitted new cables and brake levers.

The brake blocks are a bit old and I can hear them sliding on the plastic rims, so replacement seems in order.

Question What brake pad types are most suitable for plastic rims? Pads for CF are supposed to be “gentle” on the rim, which is not really needed here.

Note this is not carbon fibre, it really is plastic.

I’ve searched the site and we have no answers about plastic wheels at all.

I have tried fitting some single and dual pivot road bike calipers but they just don’t have enough reach, so I’m stuck with these stamped metal ones for now.

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Edit – more detail, and photos with some decent zoom.

Closer shot of the wheel in question The back is identical, cos there is no cassette.

Closer photo of the wheel’s brake track. Seems to be curved with age and/or wear.

Here’s what looks to be the underlying problem – the pads are old and hard and are also intended for alloy wheels.

Finally – some clarification on the “Adult” in Adult scooter. I’m 185 cm tall (6 foot 3 inches) and I can ride this with both hands on the handlebars, while standing straight. Its not a kid size. Also, I’m 9x kilos and this carries my weight fine. It goes off a normal kerb/curb okay, but not up one because of the small wheel size.

I’m not sure what the style is named, but I’ve referred to it as a Macklemore scooter, and my calls it a Scooterbike.

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Update – have replaced the pads with new ones. The caliper arms were quite bent too, forcing uneven wear in the original pads. Once brakes have bedded in, will compare braking. If no better, will source some replacement 16″ rims, probably two front wheels from kid’s bikes will do