Sigh, here goes:
Defensive maneuvers are defensive, you will only be able to 'rack' damage with them if your opponent is silly enough to approach you, while you TEMPORARILY have an advantage. You're not playing an offensive game, if you are then it does not really involve advancing, not even if you have a tire. Wario's item throw is slow, Z dropping only serves purpose if you're close to your opponent.
Walling with tires is possible to a certain, weak extent (all attacks either catch or cancel them, tires are stationary when dropped or thrown up or downwards, and therefor do not warrant a lot of (if any) action.
The combos you state are all very creative and are really fun when they work out, but they're pretty much all based on a shielding opponent. Why is your opponent shielding, and standing still? Even without tires, it just pretty much comes down to asking for a Bite, it's quite the terrible strategy.
As you said yourself, getting tires out in the first place may pose to be risky since leaving your bike onstage always has the potential to get you gimped. You do state incorrectly that opponents with tires are difficult opponents per se, that doesn't have to be true. I tend to laugh at MKs and Snakes picking up my tires, since they really pose less of a threat with a silly item that shouldn't ever hurt us in their hands. I've never really been gimped because a tire knocked me off my bike, if it'd ever come to that then you should take your recovery higher.
Our glide tossing is pathetic compared to ROB's, he throws faster, has better distances, glide tossing overall has more synergy with ROB's ground game (the basis of his game, after all) than it has with out air game. Really, terrible comparison. Wario's throw is not necessarily ineffective, it's just below average due to its terrible speed.
To conclude tires: I've never said that they're bad, but it isn't focus-on-worthy. They can net you some nice damage and everyone should know how to use them, but I don't think there's a lot of metagame development we can put to practice on this point (unless people still don't use them in the first place, I cringe every time people just randomly throw them at a shielding opponent, or overestimate the amount of hitstun on those things). Stressing the subject may have had its purpose though, I hope it did.
On nair and jab:
Nair: Actually kills fairly well at 190%. Yeah, 190%, perhaps earlier depending wtf factors like DI and such, I've killed (and am still killing) with it at surprisingly low percentages (140-150%). People tend to get greedy for the kill once they find our their uair is still and they missed their fart, and people should be satisfied with resorting to further damage racking in order to get a near guaranteed kill with less obvious killing moves, like dair and nair. Nair should be used more often overall, covering your landing as a crossup or simply in a million of situations in which most people tend to dair for the sake of using dair. Nair as a damage racker is more reliable since SDI doesn't really affect it (at higher percentages of course). While dair nets you 10% damage maybe, if your opponent doesn't SDI it immediately (really, most of the time you're just hitting with the last 3 or 4 hits anyway), nair nets you at least 9% (fresh, of course) while being quite the bit faster.
As I said earlier, it should be used more often to cover landing instead of airdodge/fair/dair. And yeah it's a decent combo breaker.
Jab: More range than grab, that's what's important. Safer than fsmash, safer than any other ground move you have really. I see people punish a laggy move when their opponent is at 60% with fsmash. Why fsmash? In a lot of cases, jab > grab > pummel > fthrow is guaranteed and does 20-21% damage. Jab has stupid amounts of frame advantage, decent range and a jab cancel does 6%. 6% is quite a lot. I'm not saying people should start spamming it, but I see people preferring other options way too often, I just gave a weak example (hurr punish laggy moves with jab cancels) but you probably understand what I'm trying to say. No longer motivated to extend this post any longer so I'm just posting it, if I have anything else to add I'll do so later, if anything is unclear feel free to comment.