Sequence of tenses (#3)

[gorikaz]

As mentioned before in another thread, according to many grammar books, it says that "when the verb in the main clause is a past tense, usually the verb(s) in the sub clause(s) must be a past tense as well." If it is true, should I change the following verb "rains" to "rained" in the example below? Does it sound strange if I change the verb from "rains" to "rained"?

(Example)
I would not go out if it rains tomorrow.(not following the rule of the sequence of tenses, right?)
I would not go out if it rained tomorrow. (Here, the verb in the main clause is past "would," so should I better change the tense of the subclause's verb from present to past?)

Which is (more) grammatically correct and used in general?

[Tdol]

The second is the standard form. With the present in the first, we would normally balance it with 'will'.

[gorikaz]

I see, the second one is the correct one.
Thank you for your help