If you have just purchased either a whitewall tyre or a raised white letter tyre, it has been delivered to you with a blue protective film over the whitewall or RWL. This is there to protect the natural white rubber whilst in transit or storage. Once you have fitted the tyres to the rim and put them on the vehicle, at this stage we recommend that you clean the blue off with warm soapy water and a soft brush like a nail brush.
If you are still building your vehicle or are not ready for the road, we suggest that you leave it on the tyre until you are ready to use the car it will protect the whitewall/RWL from impurities/UV and grease/oil etc.
We recommend that you do not lean or stack the tyres against each other and have any black touching the whitewall, as this can lead to leaching of black into the whitewall.