Chcę się pozbyć starej opony.

Because pozbyć się is a fixed reflexive verb meaning to get rid of.
You learn it as one unit:

• pozbyć się = to get rid of
• chcę się pozbyć = I want to get rid of

Here, się does not mean myself in the literal English sense. It is just part of the Polish verb.

After chcę (I want), Polish usually uses an infinitive:

• chcę iść = I want to go
• chcę kupić = I want to buy
• chcę się pozbyć = I want to get rid of

So pozbyć is the infinitive form here, and the full infinitive expression is pozbyć się.

If you said pozbywam się, that would mean I am getting rid of / I get rid of, which is a finite verb form, not an infinitive.

Pozbyć się is perfective, meaning it presents the action as a complete result: to get rid of something successfully.

That fits well with chcę:

• chcę się pozbyć starej opony = I want to get rid of the old tire

The imperfective partner is pozbywać się. That would suggest an ongoing, repeated, or process-focused action:

• pozbywać się = to be getting rid of / to get rid of repeatedly

In this sentence, the speaker means one completed result, so pozbyć się is the natural choice.

Because pozbyć się takes the genitive case, not the nominative.

Base form:

• stara opona = an old tire

After pozbyć się, it changes to genitive:

• starej opony = of an old tire

So:

• pozbyć się czego? = to get rid of what?
• starej opony is the answer, so it appears in the genitive

This is one of the key things to memorize with the verb:

• pozbyć się + genitive

Because the adjective tells you.

• starej opony = genitive singular
• starych opon = genitive plural

So in your sentence:

• starej matches a singular feminine noun
• therefore opony here means of an old tire (singular), not of old tires

This is a common Polish pattern: sometimes the noun form alone can be ambiguous, but the adjective makes the number and case clear.

The dictionary forms are:

• stary = old
• opona = tire / tyre

In the sentence they change because of gender, number, and case:

• stary → starej
• opona → opony

More exactly:

• opona is a feminine noun
• starej opony is genitive singular feminine

Opona usually means tire in American English or tyre in British English.

So:

• stara opona = an old tire / an old tyre

Depending on context, it usually means the rubber tire itself, not the whole wheel.

Because Polish often leaves out subject pronouns when the verb already shows who is acting.

• chcę already means I want
• so ja is unnecessary unless you want emphasis

Compare:

• Chcę się pozbyć starej opony. = I want to get rid of the old tire.
• Ja chcę się pozbyć starej opony. = I want to get rid of the old tire. (more emphatic)

This is very normal in Polish.

Yes. Polish word order is more flexible than English, although some orders sound more natural depending on emphasis.

Neutral:

• Chcę się pozbyć starej opony.

Other possible orders:

• Starej opony chcę się pozbyć. = It is the old tire that I want to get rid of.
• Chcę starej opony się pozbyć. = possible, but less neutral and more stylistically marked

For everyday use, Chcę się pozbyć starej opony is the best standard order.

A rough English-friendly guide:

• chcę ≈ h-tsen
• się ≈ shyeng or sheng (very approximate)
• pozbyć ≈ poz-bihch
• starej ≈ STAR-ey
• opony ≈ o-PO-nih

A few useful notes:

• ch sounds like a strong h
• ę is a nasal vowel; at the end of chcę it often sounds close to e plus nasality
• się is pronounced more like śę, with a soft ś sound
• y is not the English ee; it is a different Polish vowel

A more Polish-like pronunciation would be approximately: H-tsen sheng poz-bitch STAR-ey o-PO-nih

Not perfect, but good enough as a learner approximation.

Not exactly.

• pozbyć się = to get rid of
• wyrzucić = to throw away / discard

Sometimes they overlap, but pozbyć się is broader. You can get rid of something in many ways: throw it away, sell it, donate it, remove it, etc.

So:

• Chcę się pozbyć starej opony = I want to get rid of the old tire.
• Chcę wyrzucić starą oponę = I want to throw away the old tire.

Notice something important in the second sentence:

• wyrzucić takes the accusative
• so it would be starą oponę, not starej opony

That contrast is very useful:

• pozbyć się + genitive
• wyrzucić + accusative

A very useful pattern is:

• chcieć + infinitive = to want to do something
• pozbyć się + genitive = to get rid of something

So you can build similar sentences:

• Chcę się pozbyć problemu. = I want to get rid of the problem.
• Chcę się pozbyć tych rzeczy. = I want to get rid of these things.
• Muszę się pozbyć starego telefonu. = I have to get rid of the old phone.

If you remember just one thing, make it this:

pozbyć się is learned together, and it requires the genitive.