Bought slightly too big outer tube - options?
You can't make your front wheel sit lower without replacing the fork, and even if you switch to longer-drop brakes (I assume they're dual-pivot calipers if it's a racing-style bike), you can't easily move the mounting bolt.

The only options I can think of are:


if moving the rear wheel in the drops works, keep both tyres for the rear wheel and buy a single smaller tyre for the front (cost: 1 extra tyre)
get wider rims, to flatten the tyre's cross-sectional profile (this is a lot more expensive than just buying new tyres though, and I'd hate to speculate on what width you need to save your 2mm+) (cost: 1 or 2 wheels, depending on 1)
get a new front fork, only if 1 works (cost: 1 fork + maybe paying your local shop to cut the steerer tube)
just get new tyres and sell the old ones - say they're unused and didn't work for your bike (cost: depends on what you can sell the tyres for)