13mm X 19mm kflex from Bunnings.
If 29" glue two together, put insulation tape over the joins.
If 27.5 you'll need to shorten it to make it fit tightly.
Insert into wheel with one side of the tyre seated.
Ensure the taped seams is over the valve.
Fill with sealant and inflate.
You'll find that.
- Your bike is more quiet. A lot of bike noise is stuff just amplified by the space in the tyres.
- Lower pressures with more support is there.
- Lots more grip.
- Rim protection.
- Your ride is more damped.
I've done this on all but one set of wheels.
It's not as completed a solution as Cushcore but costs a mere fraction ($12.00) for both wheels.
If it gets damaged, just replace it. I've had mine in for easily 18 months and they're still working fine. Granted, this is across 3 bikes.
Possible watch outs.
1. The ghettocore can snug up against the valve so air doesn't come out as easily when you press the valve.
2. It can soak up sealant depending on brand. Stan's has been fine. Mitas wasn't so good.
Hope that helps.