This is grammatical:
I'm too tired to drive.
but this isn't:
I'm tired to drive.
Why? How can removing an adverb make a sentence ungrammatical?
In a sentence like “He slowly walked down the street”, you can remove the adverb and still get a grammatical sentence: “He walked down the street.” What is different about “I'm too tired to drive”?
The other answers do an excellent job explaining too adjective to infinitive, so I won't address that. I'll try to explain a different aspect of this, which might be what you're finding so surprising: specifically, how it could possibly be that removing an adverb could render a sentence ungrammatical? As you said, removing "slowly" from "He slowly walked down the street" changes the meaning a little but it doesn't make it ungrammatical. An adverb is just an optional modifier, so what could be wrong with leaving it out?
The reason removing an adverb can cause ungrammaticality is that in English, often a phrase is the unit of meaning, not the individual words. Sometimes, the meaning of a phrase doesn't derive from combining the meanings of the individual words like when you combine slowly with walked to mean slow walking. The phrase too adjective to infinitive is actually an indivisible unit of meaning. The word to doesn't express a relationship between one part of the sentence and the object of a prepositional phrase the way prepositions usually do. Instead, too and to together supply the distinctive signature of this phrase. If either of those exact words is missing, the phrase is gone. The phrase is itself like a word in the language. It just happens to consist of two words plus two slots to be filled in by other words (the adjective and the infinitive).
This drives people learning English as a foreign language crazy. In most languages, the individual words combine their meanings according to standard rules for combining meanings. English mostly does that, too, but English also makes heavy use of phrasal verbs and similar phrasal templates that are themselves indivisible units of meaning. (Actually, I think nearly all languages do this at least a tiny bit, just not to the extent that English does.)
I once spent most of a plane flight talking with a woman from Brazil. When the plane landed, I asked her, "Do you have someone to pick you up from the airport?" She said, "Why is everything always 'up' in English? Why don't you just say 'pick me from the airport'?"
It's because pick is actually a completely different verb than pick up. To pick someone means to choose them, like when children "pick" who they want on their team before playing a game. To pick someone up from the airport means to give them a ride.
Prepositions often serve as the distinctive word in the signature of phrasal verbs. Here are some more phrasal verbs that include pick:
pick on someone = bully someone, or single someone out for unfair, harsh treatment
pick up after someone = clean up someone else's mess
pick at something = repeatedly scratch or poke something with a sharp object; for example, "pick at a scab"
pick a person up = meet a person you've never met before (not a planned meeting) and go on an impromptu romantic date
pick a call up = answer a telephone call
In phrasal verbs, one of the words is always a preposition. But it doesn't function like a preposition. The up in pick up doesn't work like up in walk up the stairs, where up introduces a prepositional phrase that modifies walk. In pick up, the word up changes pick into a completely different verb! Some linguists call up a particle rather than a preposition when it plays this role, since it doesn't introduce a prepositional phrase.
Here is a consequence of all this that might be surprising: you can't replace too with a synonym. "I'm excessively tired to drive" is also ungrammatical! The problem isn't that an adverb is missing from I'm tired to drive, it's that specifically the word too is missing.
It's just like pick up: you can't replace up with a synonym or approximation like above or upward without radically changing the meaning. Pick you above from the airport is actually ungrammatical. There's no phrasal verb pick above.
When I hear I'm tired to drive, I feel disoriented. The word tired seems to be leading somewhere, but then I can't recognize a familiar phrase that starts with tired, like tired of gerund. I also can't find a way to join to into a familiar phrase with anything earlier in the sentence. Is it like in order to (for the purpose of)? No, because nobody would get tired in order to drive. Is it like toward? No, because to drive is not a prepositional phrase. It's a to-infinitive. The word to doesn't mean a direction here.
The sentence is ungrammatical because the parts don't join together. No familiar phrase starting with tired concludes in to infinitive. And no familiar kind of phrase ending in to infinitive starts with tired and gets a reasonable meaning. Normal, one-word-at-a-time combining of meanings doesn't work, either.
The construction in question is:
too adjective to verb
Examples:
I'm too tired to drive
I'm too bored to continue
I'm too dizzy to stand
The "too" here is crucial -- it's saying you're tired to such an extent that you cannot drive. Contrast this with:
almost too tired to drive
In this case, you're still indicating that you're tired, but not to such an extent that it will prevent you from driving. So, simply stating that you're "tired to drive" doesn't make clear what the impact of your tiredness is on your driving ability. Are you too tired or not?
However, there are other cases of "adjective to verb" that are used without a modifier like "too":
I'm pleased to see you
I'm excited to hear it
I'm unhappy to wait
And you can also say things like:
I'm tired of driving
But that's saying something else: not that your fatigue is so great that you're unable to drive (which "I'm too tired to drive" means), but that you're currently driving and you don't want to be doing so anymore (using "tired of" as an expression, not a statement about your actual fatigue).
I am tired to drive. (wrong)
The sentence is wrong because there is no such construction in English.
Or, rather, a similar construction exists but it serves as a kind of a passive construction:
Compare:
I am easy to please.
Here, you say that it is easy to please you. That someone will find it easy to please you.
Try to insert tired, and the sentence won't work:
I am tired to please.
In the example you provide, the full sentence goes like this:
Sometimes, I tell them I am tired to please them, though I am actually not.
It could be rephrased as:
Sometimes, in order to please them, I tell them: "I am tired", though I am actually not.
The construction
I am too tired to drive.
Works in another way: it implies
I am tired too much to be able to drive.
Exclude the too much part, and again the meaning vanishes:
I am tired to be able to drive.
The phrase "too tired to drive" is an instance of the general construction "too <adjective> to <verb>", which is used to indicate that the person or thing being described cannot (or will not) perform the action <verb> (or cannot be the object of it) because it is excessively <adjective>. Some other examples of the same construction are:
I am too busy to come. (= I cannot come, because I am so busy.)
He is too lazy to get up. (= He will not get up, because he is so lazy.)
The stone is too heavy to lift. (= The stone cannot be lifted, because it is so heavy.)
The coffee is too hot to drink. (= It is not safe to drink the coffee, because it is so hot.)
There are other similar constructions with the same or opposite meaning, such as "<adjective> enough to <verb>" or "(in)sufficiently <adjective> to <verb>", and there are also some special adjectives that can appear alone with an infinitive verb, like "ready to <verb>", "(un)able to <verb>" or "(un)willing to <verb>".
However, "tired" is not one of those special adjectives, so you cannot meaningfully say **"tired to <verb>". Indeed, it's not clear what such an expression should mean — are you tired enough to <verb>, or too tired to <verb>? Since the adjective "tired" does not carry any intrinsic sense that would allow us to distinguish between those two opposite interpretations, the phrase as a whole is essentially meaningless.
What you may be looking for, instead, is the expression "tired of <verb>ing", which has a different meaning altogether: it means that you are tired because of doing the specified action, and/or that your tiredness is specifically related to the action (i.e. that you've done the action too much, and no longer want to do it).
The reason why the verb in this construction needs to be in gerund form (i.e. with the "-ing" suffix) is because the more general construction is really "tired of <noun>"; the "-ing" suffix is needed to turn the verb into a noun describing the action (e.g. "drive" → "driving"). The same construction can be used with noun not derived from verbs, as in:
I am tired of driving. (= I have been driving too long, and no longer want to drive.)
He is tired of ice cream. (= He has eaten too much ice cream, and does not want any more of it.)
I am tired of the rain. (= It has been raining too much, and I would like it to stop.)
Another thing to note about this construction is that it's also specific to certain adjectives (many of which are participles of phrasal verbs involving the preposition "of"), such as "tired of", "afraid of", "sick of", "bored of", etc. It cannot be applied to arbitrary adjectives; you cannot say you are e.g. **"sleepy of driving", even though "tired" and "sleepy" on their own are mostly synonymous. That said, some various adjective–preposition combinations are also possible, such as, say, "eager for" or "happy with" or "accustomed to".
This is grammatical:
- I'm too tired to drive.
but this isn't:
- I'm tired to drive.
Why? How can removing an adverb make a sentence ungrammatical?
Your example #1 means that it is expected that you will not drive. And that the reason why it is expected that you won't drive is that you are too tired. Thus, your example #1:
The adverb "too" is part of the adjective phrase "too tired to drive":
where the adjective phrase "too tired to drive" is headed by the adjective "tired".
The adverb "too" is needed because it is what indirectly licenses the infinitival clause "to drive". Without the presence of "too", there is no licensor for that infinitival clause "to drive".
Your example #2, which is missing the licensor "too", doesn't seem to make much sense in the usual types of context. (Though, perhaps an unusual context could be thought up to make #2 acceptable.) If a different adjective is used instead of "tired", then sometimes it will create an acceptable example, e.g. "I'm willing to drive", which means that it is possible that I might end up driving, for I probably won't refuse a request for me to drive.
Here's some info from a vetted grammar source, the 2002 CGEL.
Page 585:
The primary sense of too is to indicate a higher degree than the maximum that is consistent with meeting some condition, achieving some purpose, actualising some situation:
[35]
i. She was too tired to continue.
ii. We didn't go out: it was too wet.
In [i ] the degree of tiredness was greater than the maximum consistent with her continuing: the sentence thus entails that she didn't continue. In this sense, too licenses an indirect complement with the form of an infinitival clause or a for phrase (too valuable for this kind of use).
This indirect complement indicates the condition, purpose, or potential situation, but does not have to be overtly expressed. In [ii ], for example, there is no complement in the wet phrase, but we understand "too wet to go out".
Notice that for [35.i ] "She was too tired to continue" entails she didn't continue. That means that she did not continue.
Page 1256-7:
1.ii. She's [too young to go to school]. -- (indirect complement)
1.iii. She's [young] to be going to school. -- (adjunct in clause structure)
. . .
In [ii ] the infinitival is a constituent of the AdjP, but is licensed by too rather than by the adjective young. It is therefore an indirect complement; . . .
While [ii ] says that she is young to a degree higher than that at which she can or should go to school, [iii ] says that she is young relative to those who go to school: it is unexpected or noteworthy that someone as young as she is should be going to school.
Notice that for [1.ii ] "She's too young to go to school" means that it is expected that she does not go to school (or that she will not go to school in the immediate future).
I am giving another answer after you edited your question:
tired to does not refer to a physical condition, but a psychological one:
Being fed up with a situation or not having the emotional strength to continue/try again. (But I'd rather use tired of.)
It stems not from being tired, but from tiring of sth."
NB: This is not an attempt to answer the OP's question but I offer it as an explanation for the meaning behind the third quote.
To win. I am unhappy because this year we have not got since the beginning a competitive car. I am tired to lose the championship at the last race; it has happened too many times in the last years
This quote is from an Italian businessman, Luca Montezemolo, who used to "run" the Ferrari team. (The article is dated 2011.) At the press conference he was probably speaking in English and the reporter(s) recorded his exact words, but he's not a native speaker. He's Italian, and although his English is quite good, it's not perfect.
In Italian the adjective stanco (tired) is also used to express disappointment, weariness or boredom. What he meant to say was:
I'm sick and tired of losing at the last race, it's happened too (often) many times in the past.
OR
I'm fed up with losing (the Grand Prix/Formula One) at the last race, it's happened too often in the last couple of years.
Note in both instances the gerund form, losing, follows the prepositions, of and with.
