Learn Hardcore Russian: Широкая улица становится тихой вечером. - The wide street becomes quiet in the evening.

широкий улица – wrong, because широкий is masculine nominative.
широкая улицу – wrong, because улицу is accusative, but here we need nominative for the subject.

How do we know that улица is the subject and not the object?

Becoming verbs like становиться usually take:
- a subject in the nominative (the thing that changes)
- sometimes a predicate also in nominative or instrumental (what it becomes)
There is no other candidate for the subject:
- улица is in the nominative form улица (not улицу, улицей, etc.).
- The adjective широкая also shows nominative feminine.

So широкая улица is clearly the subject: “The wide street becomes…”

What case is тихой and why is it used here?

Тихой is in the instrumental case, feminine singular.

Russian often uses the instrumental case for a predicative complement after verbs like:

быть (to be) in the past/future: она была врачом – “she was a doctor”
становиться / стать (to become): она стала врачом – “she became a doctor”

So:

становится тихой literally = “becomes (being) quiet”
тихой is in instrumental because it’s the “new state” of the subject after the change.

This is a standard pattern:
X становится / стал / станет + (instrumental)

Could we say широкая улица становится тихая вечером instead of тихой?

No, that sounds wrong to a native speaker.

After становиться / стать, the normal, natural forms are:

instrumental case adjective: становится тихой
or, for some adjectives, short-form adjectives (where they exist), but тихий doesn’t have a common short form that would fit here.

Using тихая (nominative) after становится breaks the usual grammar rule.
So you should use тихой (instrumental) here.

Why do we use становится at all? Why not just say “The wide street is quiet in the evening”?

Становится means “becomes / is becoming” – it emphasizes a change of state.

Широкая улица становится тихой вечером.
“The wide street becomes quiet in the evening.”
→ Focus: during the evening, the street changes from not quiet to quiet.

If you only want to say “is quiet in the evening” (a general characteristic, no emphasis on change), you might say:

Широкая улица бывает тихой вечером. – “The wide street is (tends to be) quiet in the evening.”
Or rephrase: Вечером на широкой улице тихо. – “In the evening it is quiet on the wide street.”

So становится is chosen because the speaker wants to highlight the process of becoming quiet.

Why is it тихой (adjective) and not тихо (adverb)?

Both are possible, but they have slightly different nuances:

становится тихой – тихой describes the street itself as becoming a “quiet street.”
It presents “quiet” as a quality of the noun (улица).
становится тихо – тихо is an adverb, describing the situation / atmosphere:
“It becomes quiet (there)” rather than “the street becomes quiet (as a property).”

In your sentence:

Широкая улица становится тихой вечером.
Focus on the street as an entity with the property “quiet.”

If you say:

Вечером на улице становится тихо.
It sounds more like “In the evening, it gets quiet in the street (in that area).”

Why is вечером used without a preposition? Shouldn’t it be something like в вечером?

Вечером here is the instrumental singular of вечер, used as an adverbial meaning “in the evening.”

Russian very often uses bare instrumental forms of time words to mean “at / in that time”:

утром – in the morning
днём – in the daytime
вечером – in the evening
ночью – at night

You never say в вечером. The correct form is just вечером.

So …тихой вечером = “…quiet in the evening.”

Can we change the word order, for example Вечером широкая улица становится тихой? Does it change the meaning?

Yes, you can change the word order:

Вечером широкая улица становится тихой.
Широкая улица вечером становится тихой.
Широкая улица становится вечером тихой.

All are grammatically correct and keep essentially the same basic meaning.

Differences are mostly in emphasis and rhythm:

Starting with Вечером highlights the time:
“In the evening, the wide street becomes quiet.”
Starting with Широкая улица highlights the street itself.

Russian word order is relatively flexible; the grammatical roles are shown by endings, not by position.

What is the difference between становится and станет with this sentence?

Both come from становиться / стать “to become,” but differ in tense and aspect:

становится – present tense, imperfective aspect
→ describes a regular, repeated, or ongoing process.
Широкая улица становится тихой вечером.
“The wide street (usually / habitually) becomes quiet in the evening.”
станет – future tense, perfective aspect
→ one-time, complete change in the future.
Широкая улица станет тихой вечером.
“The wide street will become quiet in the evening (on that particular evening / at that time).”

So:

становится – general tendency or process.
станет – a specific future event/change.

If I want to say “Wide streets become quiet in the evening,” how do I change the sentence?

You need the plural forms:

широкие улицы – plural nominative (subject)
становятся – 3rd person plural present
тихими – plural instrumental feminine (predicate adjective)
вечером stays the same (it does not change for plural)

So the full sentence is:

Широкие улицы становятся тихими вечером.
“Wide streets become quiet in the evening.”

How can I say simply “The wide street is quiet in the evening” (without the idea of “becomes”)?

One natural way is:

Широкая улица бывает тихой вечером.
Literally: “The wide street happens to be quiet in the evening / tends to be quiet in the evening.”

Other options with slightly different phrasing:

Вечером широкая улица тихая. – correct but more bookish / poetic.
Вечером на широкой улице тихо. – “In the evening it is quiet on the wide street.”
(Focus on the situation, not the property of the street.)

But if you want the most neutral, typical version close to English “is quiet in the evening” as a regular characteristic, бывает тихой вечером is a good choice.