According to the website WD40 is safe on rubber.
The only materials which are mentioned as being affected are polycarbonate and clear polystyrene.

äîäìê ùì äáåìí ðâîø ìôðé ùîâï äàá÷ îâéò àì äàæåø òí äçìåãä åáâìì æä âí éù ùí çìåãä ëé ùàø äèìñ÷åô îöåôä áùëáä ã÷ä ùì ùîï.
áæîï äøëéáä áëáéù òôåú ëîåéåú òöåîåú ùì âåôéí ÷èðéí.
çì÷ îäí çåãøéí àú îâï äàá÷ åîùí àì äàèí åôåøöéí àåúå.
äà÷åøãéåï îâï îôðé æä åìà îôðé çìåãä.