Not much in Dubai, drive down to Sharjah, there is few scrap shops that will cater your requirement. The authorities have clamped down on used tyre shops, bt spares i think there are few, be ready to sharpen you negotiation skills..
Al Ghandi Auto has emerged as one point for class automotive service. They are one of the largest service center in the middle region,with 5 division in 6 main location in UAE