What's the meaning for 'de' in "Tour de France"?
Solution 1:
"Tour de France" is in French, where de means of. The slightly less well-known "Giro d'Italia" and "Vuelta a España" are similarly in the local languages.
If you wrote "Tour de Hainan Island" then you would be suggesting a link to the French event, while "Tour of Hainan" would be standard English and is already used.
Solution 2:
It means 'of,' as in Tour of France. You can use 'de' if you'd like, and everyone would know what you mean. Unfortunately, guys like Donald Trump also do that sort of thing for the cheap grab at prestige.
You don't want people to think you're like Donald Trump, do you?
Solution 3:
Well since we're not speaking English any more and since Hainan is the famous Chinese Island (海南 Sea+South) I might just as well point out that the French de can be translated in Chinese by non other than ... de (的) as well.
In Taiwan, 我的腳踏車: my bicycle. In Beijing: 我的自行车.
Tour de France: "環法自行車賽".
Tour de Hainan: "環海南自行車賽" and with de if one really wishes: 海南的自行車賽
Solution 4:
It means "of", as in Tour of France. So yes, you could say "Tour de Hainan Island," even if you weren't cycling. You could walk or ride horses. As long as you were traveling around it.