Tengo un pinchazo.

Because Spanish often uses tener for things you have, including problems, sensations, and physical conditions.

So Tengo un pinchazo is structured literally as I have a puncture / I have a sharp pain.

This is very normal in Spanish. Compare:

• Tengo hambre = I’m hungry
• Tengo miedo = I’m scared
• Tengo un resfriado = I have a cold
• Tengo un pinchazo = I have a puncture / I have a stabbing pain

Even if English might sometimes phrase it differently, tener is the natural choice here.

Pinchazo comes from the idea of a prick, puncture, or sharp jab.

Depending on context, it can refer to:

• a puncture / flat tire
• a sharp stabbing pain
• sometimes a needle prick or jab

So the word has a core idea of something sharp or piercing.

Because pinchazo is a countable noun here.

Spanish treats it as a puncture, a jab, or a sharp pain, so it normally takes an article:

• Tengo un pinchazo. = I have a puncture / a sharp pain.

Without un, the sentence would sound incomplete or unnatural in standard usage.

This is different from expressions like:

• Tengo hambre
• Tengo frío

Those use nouns in more fixed idiomatic expressions, while pinchazo here is an ordinary countable noun.

Yes. It is masculine singular, which is why it uses un:

• un pinchazo

The plural would be:

• unos pinchazos = some sharp pains / some punctures, depending on context

Like many nouns ending in -o, it is masculine.

Yes, very much so. Context matters.

In everyday Spanish, it could mean:

• I have a puncture / flat tire
• I have a sharp pain

For example:

• La bici tiene un pinchazo. = The bike has a puncture.
• Tengo un pinchazo en el costado. = I have a sharp pain in my side.

If the meaning has already been given to the learner, that meaning is probably the intended one, but it is useful to know the sentence can be ambiguous without context.

You can add more detail:

• Tengo un pinchazo en la rueda. = I have a puncture in the tire.
• He tenido un pinchazo con el coche. = I got a puncture with the car.
• La rueda tiene un pinchazo. = The tire has a puncture.

In Spain, when talking about a car or bike, pinchazo very naturally refers to a puncture.

Add the body part:

• Tengo un pinchazo en la espalda. = I have a sharp pain in my back.
• Tengo un pinchazo en el pecho. = I have a sharp pain in my chest.
• Siento un pinchazo en la pierna. = I feel a sharp pain in my leg.

That makes the meaning immediately clear.

You might hear other expressions in some contexts, but Tengo un pinchazo is the most straightforward and standard way to say it.

For a physical pain, Spanish usually prefers:

• Tengo un pinchazo
• Siento un pinchazo

For a puncture, you could also say:

• He pinchado = I’ve got a puncture / I got a flat
• La rueda está pinchada = The tire is punctured / flat

So estar is possible in related phrases, but not usually as a direct replacement in exactly the same structure.

They are related, but not identical.

• Tengo un pinchazo describes the pain as a sharp stab / jab
• Me duele... simply says ...hurts

Compare:

• Tengo un pinchazo en la espalda. = I have a sharp stabbing pain in my back.
• Me duele la espalda. = My back hurts.

So pinchazo gives more information about the type of pain.

In Spain Spanish, it is pronounced approximately:

peen-CHA-tho

More precisely:

• pin sounds like peen
• cha as in chop
• zo in Spain sounds like tho because z is pronounced like the th in thin

So:

• Tengo un pinchazo ≈ TEN-go oon peen-CHA-tho

In much of Latin America, the z would sound like an s, so it would be closer to peen-CHA-so.

Yes, especially in the right context.

In Spain, pinchazo is a very normal word for:

• a puncture in a tire
• a sharp stabbing pain

So Tengo un pinchazo is a natural sentence, although in real life speakers often add context:

• Tengo un pinchazo en la rueda.
• Tengo un pinchazo en el costado.

That is because the short sentence by itself can be a little ambiguous.

Yes.

If you are talking about a tire, pinchazo works for:

• a bike
• a motorbike
• a car
• other wheeled vehicles

Examples:

• Tengo un pinchazo en la bici. = I’ve got a puncture on my bike.
• El coche tiene un pinchazo. = The car has a flat / puncture.

So the word is not limited to one type of vehicle.

That depends on the meaning.

If you mean a flat tire / puncture:

• He pinchado. = I’ve got a flat.
• Tengo una rueda pinchada. = I have a flat tire.
• La rueda está pinchada. = The tire is flat.

If you mean a sharp pain:

• Siento un pinchazo. = I feel a sharp pain.
• Me ha dado un pinchazo. = I got a sharp pain / I felt a sudden stabbing pain.
• Tengo un dolor agudo. = I have a sharp pain.

So Tengo un pinchazo is natural, but there are several nearby ways to express similar ideas.