Si tu oublies ton permis, tu risques d’avoir des problèmes au parking de l’aéroport.

In French, after si meaning if, you normally use the present tense when talking about a real possible future situation:

• Si tu oublies ton permis... = If you forget your license...

Even though the meaning is future, French does not usually use the future tense after this si.

A very common pattern is:

• Si + present, present / future / imperative

For example:

• Si tu viens, je serai content. = If you come, I’ll be happy.
• Si tu oublies ton permis, tu risques d’avoir des problèmes.

So Si tu oublieras is not correct here.

Because the verb is oublier and the subject is tu.

In the present tense, oublier is conjugated like this:

• je oublie / j’oublie
• tu oublies
• il/elle oublie
• nous oublions
• vous oubliez
• ils/elles oublient

So:

• tu oublies = you forget

The -es ending is the normal ending for most -er verbs with tu in the present tense.

Because permis is a masculine noun in French.

• un permis
• ton permis = your license/permit

French possessive adjectives must agree with the noun possessed, not with the owner.

So:

• ton permis because permis is masculine
• ta voiture because voiture is feminine

Here, permis most likely means driver’s license.

In French, permis by itself often means:

• driver’s license, especially in everyday speech

You may also hear:

• permis de conduire = driver’s license

So in this sentence, oublier ton permis most naturally means to forget your driver’s license.

Tu is the singular informal word for you.

So this sentence is addressing:

• one person
• in an informal context

If you wanted a formal or plural version, you would say:

• Si vous oubliez votre permis, vous risquez d’avoir des problèmes au parking de l’aéroport.

So the choice between tu and vous depends on the relationship and situation, not on grammar alone.

Risquer de + infinitive means to risk doing something or, very commonly, to be likely to have / run the risk of having something happen.

So:

• tu risques d’avoir des problèmes means
• you risk having problems
• you may well have problems
• you could end up having problems

It often suggests a warning.

Other examples:

• Tu risques de tomber. = You might fall.
• Il risque de pleuvoir. = It might rain.

So here it has the sense of there may be trouble for you if this happens.

Because French usually contracts de before a vowel sound.

• de + avoir becomes d’avoir

This is called elision.

You see the same thing in many places:

• d’accord
• d’habitude
• l’aéroport instead of le aéroport

So tu risques d’avoir is just the normal form of tu risques de avoir, and the uncontracted version is not used.

French often uses the plural des problèmes where English also often says problems.

• avoir des problèmes = to have problems / to run into problems

It sounds natural and idiomatic. You could theoretically say un problème in a different sentence, but here des problèmes suggests possible trouble in a general sense.

For example:

• Tu vas avoir un problème. = You’re going to have a problem.
  This sounds more like one specific issue.
• Tu risques d’avoir des problèmes. = You risk having problems.
  This sounds broader and more natural here.

Because au = à + le.

• le parking = the parking lot / car park / parking area
• à le parking contracts to au parking

So:

• au parking = at the parking lot / in the parking area

This is a very common contraction in French:

• à + le = au
• à + les = aux

Examples:

• au restaurant
• au bureau
• aux États-Unis

Not exactly. In French, un parking is usually a parking lot, car park, or sometimes a parking garage/parking area.

So:

• au parking de l’aéroport = at the airport parking lot / in the airport car park

French borrowed the English-looking word parking, but it is used as a noun for the place, not for the activity of parking.

So English speakers should be careful:

• English parking = the act of parking
• French un parking = a parking area

Because aéroport starts with a vowel, and French uses elision again:

• de + le would normally become du
• but before a vowel, you use de l’

So:

• de l’aéroport = of the airport / at the airport

Compare:

• le parking du supermarché = the supermarket parking lot
• le parking de l’aéroport = the airport parking lot

You cannot say du aéroport.

Yes. Risquer de adds the idea of danger, possibility, or warning.

Compare:

• Tu as des problèmes au parking de l’aéroport.
  = You have problems at the airport parking lot.
  This states it as a fact.

• Tu risques d’avoir des problèmes au parking de l’aéroport.
  = You risk having problems at the airport parking lot.
  This means it may happen if you forget your license.

So risques d’avoir is not just neutral description; it warns about a possible consequence.

Yes, you could, but the meaning is slightly stronger and more direct.

• tu risques d’avoir des problèmes = you may have problems / you risk having problems
• tu auras des problèmes = you will have problems

The original sentence sounds a bit less absolute and more like a warning about likely consequences.
Your version sounds more certain.

So both are grammatical, but they do not feel exactly the same.

Mostly yes, which makes this sentence fairly approachable for English speakers:

• Si tu oublies ton permis = If you forget your license
• tu risques d’avoir des problèmes = you risk having problems
• au parking de l’aéroport = at the airport parking lot

The main things that are especially French are:

• present tense after si
• contractions like d’avoir, au, de l’
• the idiomatic use of risquer de
• un parking meaning a parking lot/car park

So the overall structure is familiar, but some of the grammar details are different from English.