How do I know when to spell a word with "r-" or "wr-"?
For example, (wr)ap and (r)ap, (wr)ing and (r)ing. Both sets have the same R sound but different spellings.
Is there a way of working out which to use, or do I simply have to learn each word?
How do I know when to spell a word with "r-" or "wr-"?
For example, (wr)ap and (r)ap, (wr)ing and (r)ing. Both sets have the same R sound but different spellings.
Is there a way of working out which to use, or do I simply have to learn each word?
No. There is no way other than to learn them.
[Words starting with "wr-" are almost always native English words, from Germanic roots, rather than borrowings from French or Latin; but that does not really give you much help].
You have to get it right by reading written words instead of focussing on pronunciation. Once you will practice enough usage, you can understand what exactly the person is saying. Try to comprehend the context and you're good to go. Also, even though they sound almost same, there is 1% dissimilarity which you'll find, like commented by @SovereignSun.