Loosen the nut holding the wheel using 17mm wrench and take pot the tire.
Remove the five screws that hold the brake disk in place using torx 20.
Push the valve inside the hub. It’s best to use a plastic tool for the job.
Push the tire evenly on all sides out of the hub.
Now that you have access to the tube you can either patch it or replace it with a new one.
Fit the tire and tube on the hub starting with the valve. Make sure that the valve points toward the outside of the hub. Try to insert the hub into the tire evenly on all sides. If you’re having difficulties you can use soapy water for lubrication.
Press the valve so it comes all the way through the hub.
Put the brake disk and tighten the the screws. There’s no need to overtighten them as this may damage the plastic hub and slip.
Inflate the tire to 3.5bar / 50psi. Make sure that both bearings are in place – one into a slot on each side of the hub. Mount the assembled wheel onto the axle and lock it with the 17mm nut. The wheel should be able to spin freely to avoid damaging the bearings