Google Steelcraft and find the contact page. Write them an email asking this very question

I’d google it to try and find it.

Try baby shops eg baby bunting or rung up manufacturer and they’ll have stockist that sell their parts.

Gumtree?

The website is great for buying the add ons

Gumtree, eBay and a search online would be my first to to places.

eBay is always a good place to look too. Otherwise check out karlisles.com.au

Gumtree is your friend. What do you mean by ‘air tyres’? Of you mean the inner tube, bike shops sell them, just take one out and get the numbers off it or take it in.

im sorry I cant help you, but I would also love to know where I can buy extras