Maximum size of UIImage tiles for iPhone 4

Question

I have an iPhone app containing a large static image, which is sliced into 1024x1024 tiles and put in an UIScrollView. I'm not clear whether I can use larger tiles on the iPhone 4.

If I want to support a double-res image for iPhone 4, should I:

1. Create 2048x2048 tiles with a @2x suffix or
2. Create 4 times as many 1024x1024 tiles and write logic to load in these tiles on the iPhone 4