A while ago I came across a Primera / G20 website that had a list of possible alloy/tyre size combinations and the circumference difference between them all.
I can't find that site now!!

Does anyone know what the URL is?

Been looking at Alloy prices, they come with 205/40R17 tyres but costs more to get 215/45R17. How much difference is there between the 2?

cheers