Jaki rodzaj opony wybierasz?

A word-by-word breakdown is:

• jaki = what kind of / what sort of
• rodzaj = kind, type
• opony = of a tire
• wybierasz = you choose / you are choosing

So the structure is basically:

Jaki rodzaj + opony + wybierasz?
= What type of tire are you choosing?

Because jaki has to agree with rodzaj.

The noun rodzaj is:

• masculine
• singular
• in this sentence, accusative in form, but for a masculine inanimate noun like rodzaj, the accusative looks the same as the nominative

So the matching form is jaki.

Compare:

• jaki rodzaj = what kind/type
• jaka opona = what tire
• jakie opony = what tires

Even though opona is feminine, jaki does not agree with opona here. It agrees with rodzaj.

Because opony depends on rodzaj, not directly on wybierasz.

The main object of wybierasz is rodzaj:

• wybierasz rodzaj = you choose a type

Then Polish uses the genitive after rodzaj:

• rodzaj czego? = type of what?
• rodzaj opony = type of tire

So:

• rodzaj = the thing being chosen
• opony = tells you what kind of thing that type refers to

That is why you do not use oponę here.

It is genitive singular of opona.

The basic forms are:

• nominative: opona
• genitive: opony
• accusative: oponę

Here you need the genitive because of rodzaj:

• rodzaj opony = type of tire

This is a very common pattern in Polish:

• rodzaj auta = type of car
• kolor domu = color of the house
• numer telefonu = phone number

Literally, it is singular: type of tire.

But in practice, singular can be used in a general, category-like sense. So it often means something like:

• what type of tire
• what kind of tire
• what tire category

Depending on context, Polish speakers might also say:

• Jaki rodzaj opon wybierasz? = What type of tires are you choosing?
• Jakie opony wybierasz? = What tires are you choosing?

So the singular here does not always mean one physical tire. It can refer to the general type.

Wybierasz is the present tense of the imperfective verb wybierać.

It can mean:

• you choose
• you are choosing
• sometimes, depending on context, you’re choosing / planning to choose

Because it is imperfective, it focuses on the process or general act of choosing.

Compare:

• wybierasz = you choose / are choosing
• wybierzesz = you will choose

So if you wanted a more clearly future meaning, you could say:

• Jaki rodzaj opony wybierzesz? = What type of tire will you choose?

Yes, Polish word order is fairly flexible, but the original sentence is the most neutral and natural version.

Neutral:

• Jaki rodzaj opony wybierasz?

Other orders are possible, but they add emphasis or sound less neutral:

• Wybierasz jaki rodzaj opony? = more like an echo question or surprise
• Jaki rodzaj opony ty wybierasz? = emphasis on you

For a learner, the safest default is the original order.

It is informal, because wybierasz means you addressed to one person in a normal, non-formal way.

If you want to be formal/polite, Polish usually uses Pan or Pani:

• Jaki rodzaj opony Pan wybiera? = What type of tire are you choosing, sir?
• Jaki rodzaj opony Pani wybiera? = What type of tire are you choosing, ma’am?

In everyday conversation, the informal version is fine with friends, family, children, or peers.

Jaki usually asks about type, quality, or kind.

So:

• Jaki rodzaj opony wybierasz? = What kind/type of tire are you choosing?

Który is more like which one, usually when choosing from a specific known set.

So if several tire types were listed already, który could be possible:

• Który rodzaj opony wybierasz? = Which type of tire are you choosing?

But without a specific list in front of you, jaki is the more natural choice.

A rough English-friendly pronunciation is:

YA-ki RO-jzai o-PO-nih vih-BYE-rash

A few useful sound notes:

• j sounds like English y
• w sounds like English v
• rz sounds like a hard zh
• cz / sz / rz / ż are common Polish consonant sounds that may take practice

Stress usually falls on the second-to-last syllable:

• JA-ki
• RO-dzaj
• o-PO-ny
• wy-BIE-rasz

So the rhythm is: JA-ki RO-dzaj o-PO-ny wy-BIE-rasz?

Yes, but it means something slightly different.

• Jaką oponę wybierasz? = Which/what tire are you choosing?
• Jaki rodzaj opony wybierasz? = What type of tire are you choosing?

The shorter version asks more directly about the tire itself.
The original sentence asks specifically about the type/category.

So if the distinction between winter, summer, all-season, etc. matters, Jaki rodzaj opony wybierasz? is more precise.