Q - Why is Ukraine asking for more tanks, long range weapons and armoured vehicles?
A - Because Russia destroyed all the others already.

Send your tanks, it won't make any difference,
It'll just drag out the war and get more Ukrainians killed
If fighting to the last Ukrainian is what your actual plan is.
- The meat grinder doesn't care.

AC,
Extrapolating from US General Mark Milley's statement that "it will be difficult for Ukraine to expel Russian troops from all of Ukraine (incl Crimea) in 2023" to "Ukraine will lose the war" is wishful thinking. Likewise wanting powerful tanks that way outclass Russia's 70's designed tanks is to smash through Russian lines. (Germany has now approved the transfer of Leopard 2 tanks from Poland and Finland) The other armoured vehicles arriving shortly will give Russia a huge headache. Russia on the other hand is losing tanks faster than it can replace them, it's running out of ammunition and precision missiles.

While Russia is still a long way from economic collapse, things are a long way from rosy. Its oil and gas revenues have halved to the point where the sales price is just above the cost of extraction, its internal airlines are on the edge of collapse or catastrophe, and the cost of the war is ever-increasing.

2022 was a disaster for Russia, and 2023 is not looking much better.

In reversal, US poised to approve Abrams tanks for Ukraine
http://apnews.com/article/us-m1-abrams-tanks-ukraine-russia-249de5c301a9bf83b5f3ac2182076a02

"The other armoured vehicles arriving shortly will give Russia a huge headache."
Yes but it's not yet enough to make a difference.
Neither side will back down and the West will continue to escalate so we'll see what happens.
It's getting closer to being WWIII.

"Russia on the other hand is losing tanks faster than it can replace them, it's running out of ammunition and precision missiles."
- That depends on who's telling the story.
I've heard that Russias current industrial capacity is 250 new T90s per year and 600 T72 modernisations per year

Ukraine Russia War Latest w. Col. Doug Macgregor
http://youtu.be/K74GonVNYO4

AC,

The US is sending 30 M1s, Germany Poland and Finland are sending 14 Leopards each and the UK is sending 14 Challenger 2s. That Ukraine is getting about 100 Bradley which in Iraq killed more T72 than the M1s should worry Putin. All of the above tanks vastly outclass the T72 and T90s

Russia is losing about 60 tanks a month and as you said can build 250 T90s a year. The ability to upgrade T72s only works if they haven't been turned into scrap iron by a javelin or other ATGM of which the Ukrainians now have more than 90 000.

That there is visual proof of 3 Russian helicopters and 2 SU 25s being shot down in the last couple of days is making a prolonged war virtually impossible for Russia.

Russia's shortage of ammunition and the wear on its guns has resulted in a 75% drop in artillery fire.

The crude and gas ban by the EU and price cap is already costing Russia more than $45bn p.a. and the prohibition on refined products on the 5th of Feb will cost Russia nearly $20bn p.a. more especially with Russia already running a large budget deficit. While Russia is not in immediate danger of financial collapse, things are going to get grim by the end of the year.

This is not a war that Russia can win.

"The ability to upgrade T72s only works if they haven't been turned into scrap iron by a javelin or other ATGM of which the Ukrainians now have more than 90 000."

Russia has over 10,000 tanks in storage
(in various states of disrepair)

Tow missiles only have a 10% hit ratio when used by experienced crews, Leba

US reports shortage of Javelins, Stingers after Ukraine aid
http://www.jpost.com/international/article-705893

This chart explains why the US is running low on missiles
http://qz.com/this-chart-explains-why-the-us-is-running-low-on-missil-1849945208

Ukraine can't replace any of their stuff faster than they are losing it.
The West has scrounged all former soviet countries and scraped up what it can but it's not enough.
Russia keeps destroying them.
Western tanks are heavier, in the case of the Bradleys they have thinner tracks, they will get bogged down, as well as this you need to first train crews for all this equipment and there are serious logistical issues in regards to maintaining them, and Russia has strengthened all its defenses

- And nothing a good swarm of Orlan + Geranium 2 drones or Russian Kornets can't fix.
Ukraine isn't the only one with manpads.
http://youtu.be/-2Io7IWwe5Y

Seriously, the West wants to pick a fight with Russia overthrowing Ukraine and bombing the citizens of the Donbass for the last 8 years to get a war going and now they want to patch together a new army, new air force, new tanks, new armoured vehicles, more javelins and stingers and artillery?

Why?

All Ukraines stuff which was built up over 8 years from 2014 by the West plus all their existing Soviet inherited hardware is gone.

And what sort of a plan was this?
- No plan, the West has no plan for this.
The West never planned for this, they thought Russia would fold via the sanctions, that it would create a political crisis that would result in Putin's ousting.