İç lastik dış lastiğin altında kaldı.

They are best understood as adjective + noun combinations:

• iç = inner, inside
• dış = outer, outside
• lastik = tire / rubber tire

So:

• iç lastik = inner tire, usually inner tube
• dış lastik = outer tire, the outer rubber tire

In everyday Turkish, these combinations are very common and feel almost like fixed terms, especially in bicycle or vehicle contexts.

Because Turkish usually expresses under X, on X, in front of X, etc. with a special structure:

• X-in / X-ın / X-un / X-ün
• plus a location word such as alt, üst, ön, arka
• and usually a case ending

So:

• dış lastiğin altında = under the outer tire

This literally breaks down as something like:

• dış lastiğ-in = of the outer tire
• alt-ı-nda = at its underside / under it

This is the normal Turkish pattern. Similar examples:

• masanın altında = under the table
• arabanın içinde = inside the car
• evin önünde = in front of the house

So dış lastik altında would sound incomplete or unnatural in standard Turkish.

Altında can be broken into parts:

• alt = lower part, underside, bottom
• -ı = third-person possessive suffix, giving altı = its underside / the bottom of it
• -nda = locative ending -de/-da, with a buffer/consonant effect here, meaning at / in / on

So:

• altında = at its underside, under it

In natural English, we simply say under.

This same pattern appears in many common expressions:

• üstünde = on it / on top of it
• önünde = in front of it
• arkasında = behind it
• içinde = inside it

Because it takes the genitive ending here: -in / -ın / -un / -ün, meaning something like of.

Starting from lastik:

• base form: lastik
• with genitive: lastiğin

Two things happen:

1. The suffix is added.
2. Final k often softens to ğ when a vowel-initial suffix is attached.

So:

• lastik
  • -in → lastiğin

This kind of change is very common:

• çocuk → çocuğun
• renk → rengin
• yemek → yemeğin

It is the genitive case ending.

In this sentence, dış lastiğin altında literally means at the underside of the outer tire or more naturally under the outer tire.

The genitive ending shows that altı belongs to or is associated with dış lastik.

This is a very common Turkish pattern:

• kapının önü = the front of the door
• evin arkası = the back of the house
• koltuğun altı = the underside of the seat / under the seat

So lastiğin is not a random form; it is there because Turkish builds these location phrases through a possessive structure.

Kaldı is the past tense of kalmak.

Kalmak often means:

• to remain
• to stay
• to be left
• to end up

In this sentence, it gives the sense that the inner tube ended up or was left under the outer tire.

So depending on context, kaldı can suggest more than a simple neutral location. It can imply a result of some event, such as getting trapped there.

That is why it works well here. It is not just describing position; it can also suggest the outcome:

• the inner tube got stuck under the outer tire
• the inner tube ended up under the outer tire

Turkish has no articles like English the or a/an.

Whether something is understood as definite or indefinite usually comes from:

• context
• word order
• case marking
• the type of noun phrase used

So iç lastik can mean:

• an inner tube
• the inner tube

And dış lastiğin altında can mean:

• under an outer tire
• under the outer tire

The exact meaning depends on context. If your learning material gives the inner tube ended up under the outer tire, that is a very natural interpretation.

The subject is İç lastik.

It is the thing that kaldı:

• İç lastik = the inner tube
• dış lastiğin altında = under the outer tire
• kaldı = remained / ended up

So the sentence structure is basically:

• Subject
  • location phrase
    • verb

No, Turkish word order is flexible, although some orders are more neutral than others.

The given sentence:

• İç lastik dış lastiğin altında kaldı.

is a normal, neutral way to say it.

You could also move parts around for emphasis, for example:

• Dış lastiğin altında iç lastik kaldı.
• İç lastik kaldı dış lastiğin altında.

These may sound more marked or context-dependent. In ordinary usage, the original order is the safest and most natural for learners.

Also remember that Turkish often puts the verb at the end, which is exactly what happens here with kaldı.

Yes. In practical usage, iç lastik often specifically means inner tube, not just a literally inner tire.

Likewise, dış lastik often refers to the outer tire itself, especially in bicycle-related contexts.

So even though the words are literally:

• iç = inner
• dış = outer
• lastik = tire

the most natural English translation may depend on the situation. Very often:

• iç lastik = inner tube
• dış lastik = tire / outer tire

Because iç lastik is the subject, and Turkish subjects normally appear in the basic form with no special ending.

If you said iç lastiği, that would usually be the accusative form, often used for a definite direct object.

Compare:

• İç lastik patladı. = The inner tube burst.
• İç lastiği değiştirdim. = I changed the inner tube.

In your sentence, the inner tube is not an object; it is the thing that remained / ended up somewhere. So the plain form iç lastik is correct.

In lastiğin, the ğ usually does not sound like a strong English consonant.

A simple learner-friendly way to think of it is:

• las-ti-in or las-tii-n with a slight lengthening or smoothing between vowels

So ğ often:

• lengthens the preceding vowel,
• or creates a gentle glide,
• rather than making a hard sound.

You do not need to force a strong g sound here. A softer pronunciation will sound more natural.

Yes, absolutely. This sentence is a great model for a very common Turkish structure.

Pattern:

• X-in
  • location noun
    • possessive + case

Examples:

• masanın üstünde = on the table
• evin önünde = in front of the house
• arabanın arkasında = behind the car
• kutunun içinde = inside the box
• sandalyenin altında = under the chair

So if you understand dış lastiğin altında, you are learning a very useful general pattern, not just one sentence.