Which is right, the Tiger should stay impenetrable at this stage frontally past 900m and past 1300m for the sides. Rear hits... Well.... Engine dies. But this is a GENEROUS estimate compared to HISTORICAL FACTS:
A report prepared by the Waffenamt-Prüfwesen 1 gave the calculated probability of perforation at range, on which various adversaries would be defeated reliably at a side angle of 30 degrees to the incoming round.
The Wa Pruef report estimated that the Tiger's 88 mm gun would be capable of penetrating the differential case of an American M4 Sherman from 2,100 m (1.3 mi) and the turret front from 1,800 m (1.1 mi), but the Tiger's 88 mm gun would not penetrate the upper glacis plate at any range. The M4 Sherman's 75 mm gun would not penetrate the Tiger frontally at any range, and needed to be within 100 m to achieve a side penetration against the 80 mm upper hull superstructure. The Sherman's upgraded 76 mm gun might penetrate the Tiger's driver's front plate from 600 m, the nose from 400 m and the turret front from 700 m. The M3 90 mm cannon used as a towed anti-aircraft and anti-tank gun, and later mounted in the M36 tank destroyer and finally the late-war M26 Pershing, could penetrate the Tiger's front plate at a range of 1,000 m using standard ammunition, and from beyond 2,000 m when using HVAP.
Soviet ground trial testing conducted in May 1943 determined that the 8.8 cm KwK 36 gun could pierce the T-34-76 frontal beam nose of 140 mm thickness from 1500 m, and the front hull from 1500 m. A hit to the driver's hatch would force it to collapse inward and break apart.[f] According to the WaPrüf, the Soviet T-34-85's upper glacis and turret front armour would be defeated between 100 and 1,400 m (0.062 and 0.870 mi), while the T-34's 85 mm gun would penetrate the front of a Tiger between 200 and 500 m (0.12 and 0.31 mi). The 120 mm hull armour of the Soviet IS-2 model 1943 would be defeated between 100 and 300 m (0.062 and 0.186 mi) at the driver's front plate and nose. The IS-2's 122 mm gun could penetrate the Tiger's front armour from between 500 and 1,500 m (0.31 and 0.93 mi). However, according to Steven Zaloga, the IS-2 and Tiger I could each knock the other out in normal combat distances below 1,000 m. At longer ranges, the performance of each respective tank against each other was dependent on the crew and the combat situation.
The British Churchill IV would become vulnerable to the Tiger at between 1,100 and 1,700 m (0.68 and 1.06 mi), its strongest point being the nose and its weakest the turret. According to an STT document dated April 1944, it was estimated that the British 17-pounder, as used on the Sherman Firefly, firing its normal APCBC ammunition, would penetrate the turret front and driver's visor plate of the Tiger out to 1,900 yards (1,700 m).
When engaging targets, Tiger crews were encouraged to angle the hull position 45 degrees to the Mahlzeit Stellung of 10 ½ or 1 ½ o'clock. This would maximize the effective front hull armour to 180mm and side hull to 140mm, making the Tiger impervious to any Allied gun up to 152 mm. Unlike the lighter Panzer IV and Panther tanks, the Tiger's thick side armour gave a degree of confidence of immunity from flank attacks. The tank was also immune to Soviet anti-tank rifle fire to the sides and rear. Its large calibre 8.8 cm provided superior fragmentation and high explosive content over the 7.5 cm KwK 42 gun. Therefore, comparing the Tiger with the Panther, for supporting the infantry and destroying fortifications, the Tiger offered superior firepower. It was also key to dealing with towed anti-tank guns, according to German tank commander Otto Carius: