La pneŭo estas sur la rado.

• la = the
• pneŭo = tire
• estas = is / are / am
• sur = on
• la = the
• rado = wheel

So the sentence is built very directly: The tire is on the wheel.

In Esperanto, -o is the standard noun ending. That means both pneŭo and rado are nouns.

This is one of the most regular parts of Esperanto grammar:

• -o = noun
• -a = adjective
• -e = adverb
• -i = infinitive verb

So:

• rado = wheel
• rada = wheel-related / wheeled
• pneŭo = tire

The ŭ in Esperanto is a very short w-like sound. In pneŭo, it combines with e to make eŭ.

A rough English-friendly pronunciation of pneŭo is PNEH-wo.

A few notes:

• The first p is pronounced, unlike in English pneumatic where the p is usually silent.
• ŭ is not a full vowel by itself here; it glides like a short w.
• Stress in Esperanto normally falls on the second-to-last syllable, so pneŭo is stressed on pneŭ.

Because both nouns are definite:

• la pneŭo = the tire
• la rado = the wheel

Esperanto uses la the same way English uses the. If both things are specific and known from context, you use la with both.

For example:

• La libro estas sur la tablo. = The book is on the table.

No. Esperanto has no indefinite article.

So:

• pneŭo can mean a tire or just tire, depending on context
• la pneŭo specifically means the tire

That means Esperanto only has one article: la.

Estas is the present tense form of esti, which means to be.

So:

• mi estas = I am
• vi estas = you are
• li estas = he is
• ili estas = they are

Unlike English, Esperanto does not change the present tense form depending on the subject. It is always estas.

Because la rado is the object of the preposition sur, and here it shows location, not motion toward something.

In Esperanto, -n is often used for:

1. the direct object
2. direction toward a place in some expressions

Here, sur la rado means on the wheel as a location, so no -n is needed.

Compare:

• La pneŭo estas sur la rado. = The tire is on the wheel.
• Mi metas la pneŭon sur la radon. = I put the tire onto the wheel.

In the second sentence, sur la radon shows movement onto the wheel.

Sur usually means on, on top of, or on the surface of.

In this sentence, it is being used in a practical, everyday way: the tire is on the wheel.

That is a normal and understandable choice. In real-life mechanical contexts, someone might choose a more specialized phrasing depending on what exactly they want to emphasize, but for a basic learner sentence, sur la rado is perfectly natural and clear.

Yes. Esperanto word order is more flexible than English word order, because grammar endings do a lot of the work.

The neutral order here is:

• La pneŭo estas sur la rado.

But other orders are possible for emphasis, such as:

• Sur la rado estas la pneŭo.

That sounds more marked or stylistic, something like On the wheel is the tire.

For beginners, the standard subject-verb-prepositional phrase order is the safest choice.

It is the subject because it is the thing being described as existing in a location.

The structure is:

• La pneŭo = subject
• estas = verb
• sur la rado = prepositional phrase describing location

A useful clue is that sur la rado begins with a preposition, so that whole part functions as a location phrase, not as the subject.

Not usually. Estas sur la rado describes a state or location: the tire is on the wheel.

If you want to express the action of putting it there, you would normally use a different verb, such as:

• La pneŭo estas metata sur la radon. = The tire is being put onto the wheel.
• Mi metas la pneŭon sur la radon. = I put the tire onto the wheel.

So the original sentence describes where the tire is, not the action of mounting it.

You add -j to plural nouns.

So:

• La pneŭo estas sur la rado. = The tire is on the wheel.
• La pneŭoj estas sur la radoj. = The tires are on the wheels.

Notice that:

• pneŭo → pneŭoj
• rado → radoj
• estas stays the same

A rough English-friendly guide is:

lah PNEH-wo ESS-tahs soor lah RAH-doh

A few pronunciation reminders:

• a sounds like the a in father
• e sounds like e in bet, but cleaner
• u sounds like oo in food
• r is usually trilled or tapped
• stress goes on the second-to-last syllable of each word:
  • LA
  • pneŬO
  • ES-tas
  • SUR
  • LA
  • RA-do

So the natural stress is: la pneŬo ES-tas sur la RAdo.