How long before a main battle tank design becomes obsolete?

Pakistan has one called the Al-Khalid. Been fielded for about 10 years, has done well in the present insurgency.

As I noted above, the Merkava was also designed as an open battlefield tank; it just happens to be very good at urban combat too.

Given the devasting power of modern anti-tank weapons (srface-srface and air-srface missiles), is it worthwhile to develop new tanks?
A modern MBT costs a bundle, ses tremendos amounts of fuel, and exposes a human crew to great risk.
A air-surface missile can blow the tracks off a tank, rendering it useless.

Air power isn’t exactly the complete king of the battlefield. It has its own problems and pitfalls.

Indeed, tanks have always been vulnerable to anything sufficiently powerful, whether it was 12-inch artillery shells, 2000-lb bombs dropped from the air, or an infantryman getting in a lucky strike at a weak point. The question is, what things are going to be in a position to harm a tank, and what are their vulnerabilities in turn? So far tanks have been a worthwhile proposition when in the right place at the right time. If advanced electronics make smart antitank missiles possible, it also makes things like active defense systems possible. I would say tanks aren’t yet facing the mechanized version of Agincourt.

I wouldn’t make that change. Quantity has a quality all of its own, as Stalin probably didn’t say. A T-55 will not be much good against a modern tank, but if used correctly, it’s still very bad news for infantry. You’re equally dead if hit by shrapnel from a 100 mm rifle or a 120 mm smoothbore. (Or, more likely, from coax machine gun fire, which hasn’t changed that much anyway.)

Fielding a modern MBT takes a huge support train with a ton of very skilled people. The older designs can be kept running somewhat easier, and with 250 tanks, you have plenty of spare parts on the hoof, so to speak.

Quite the contrary, I’d rather apply my best forces against whatever forces they’d be most effective against, and in turn ensuring that the enemy’s forces engage those forces of mine they are least effective against. That is to say, my Tier I armored forces should be ripping through their Tier III armored forces and supply lines, and their Tier I forces should be introduced to an appropriate combination of precision and saturation air and artillery strikes.

All this is in a perfect world, of course. No doubt the other guys are endeavoring to do the same, and either we might find our first string guys going up against each other, or else even some of their Tier I guys getting the jump on some of my less appropriately equipped troops.

And yeah, say you have an army with Cold War era tanks (T-55s seem to be the tank that turns up everywhere). Assuming that you don’t have modern anti-armor weapons, that 60 year old tank is going to be every bit as impervious to the 5.56 and 7.62 firearms that modern infantry is equipped with as it would have been against the rifles and machine guns of the 1950’s.

Hell, even a T-38 or an M-4 Sherman will give you endless grief if you come across one in operating condition and you equipped with only anti-infantry weaponry. That said, I can definitely see most modern infantry units carrying a supply of anti-armor rockets (such as the Soviet RPGs or American weapons such as the LAW or AT4 rocket launchers), most especially if they know the other side has tanks (tanks are not the easiest weapons to be sneaky about having. For one thing, who can resist tearing around in the mud in them?)

It’s very difficult to debate the equivalence of tanks without considering the context. A US armoured unit will have air support, artillery, intelligence and other elements that other nations may be unable to match. Terrain, experience, etc, will all play a role that could swing an otherwise ‘equal’ engagement.

I was going to mention the T-95 and Black Eagle as Russian challengers for the modern MBT stakes, but a quick search reveals that both programmes were cancelled. Oh well!