The /eə/ diphthong is spelled <are>, <air> or <ear>. The /ʊə/ diphthong is spelled <ure>, <our> or <oor>.
This is a contrast between two diphthongs with widely different starting positions and a difference of lip rounding. It is not a problem for learners.
Interesting pairs include:
The density figure is 2.47%. The set makes 15 semantic contrasts giving a loading of 57.7%.
bairn bourn bairns bourns bare boor bares boors bear boor bears boors bearish boorish dare dour hairy houri lair lure lairs lures laird lured layer lure layers lyres layered lured mare moor mares moors pair poor share sure spare spoor spares spoors tare tour tares tours tear tour tears tours tearing touring
John Higgins, Shaftesbury, December 2009