I modeled this for my little (autistic) girl Zoe. She loves Peppa.. especially that part when they go on schooltrip with the blue bus. Used different color PLA. No painting required if you have those colors. Everything glued together with superglue. At the end it will be a robust thing. My 20kg girl even can stay on it and it holds up.
You need 4pcs 608ZZ bearings. Those will be the tires.
It should be printed at 100% scale because the bearings will fit only then.
Feel free to contact me if you run into any problems. I will try to help.
little video on bearings: https://drive.google.com/open?id=1-NMvhk65GuNqORC4-ii3ih4OdDx9nxyz
Glue everything together, put bearings on undercarriage before attaching the side panels