No, you need the spell slots to cast from.
The question is whether or not you gain bonus spells to spell levels via a high spell-casting stat that you aren't able to cast from class advancement. There is no text that says bonus spells granted by a high spellcasting stat don't extend to levels not yet accessible by natural progression. However, the rules as intended definitely mean to limit that as evidenced by levels that grant 0 spells per day in a new spell level. So, the answer is no, because Wizards break the game enough.
The next question is whether or not you gain bonus spells from spell levels you can cast from a source that is neither class advancement nor a high spellcasting stat (e.g. Nightmare Spinner 1's Bonus Spells (Ex) class feature, Eldritch Corruption feat, Earth Spell feat, metamagic reduction (Arcane Thesis feat, Practical Metamagic feat, Easy Metamagic feat, Metamagic School Focus, etc.) + Heighten Spell feat, Precocious Apprentice feat, Dragon's Tear optional material spell component, etc.). Generally, the answer is no to this question too if the answer is no to the previous question.
P.S. Remember, Wizards can't prepare spells from other spell-books without 2 Spellcraft checks (unless it's one of such wondrous items that specifically allow you to do so). (PHb, p.178)