The 85mm gun used on the T-34/85 was very similar to the Soviet 85mm AA gun, which was tested by the Soviets against the Tiger. This testing showed that the 85mm could penetrate the Tiger's front at 1000m, but couldn't at a range of 1500m. However, multiple impacts from that range did cause serious cracking and spalling of the armour plates, which would have made the tank useless in combat, and might kill the crew. Similarly, Soviet tests of the D-5 give an 75% chance of penetration at 1000m for 102mm of armour at 90 degrees, about enough to penetrate a Tiger I's front hull. This is consistent with Zaloga's work - the T-34/85 could penetrate the Tiger, but only at ranges where it could be killed itself, as would the IS-2 if armed with the 85mm. Soviet testing of 122mm guns against Tigers showed that the Tiger's armour wasn't substantial enough to protect against it. Testing of the 122mm A-19, predecessor to the D-25 used on the IS-2, demonstrate this well, with one shell impact from 1500m knocking the Tiger's turret off its turret ring and moving it back 540mm. Testing against Tiger IIs, this time with the D-25, also favoured the Soviet guns - AP ammo fired with a reduced charge from 2500m was able to penetrate the Tiger II's turret front, knocking away large amounts of armour and cracking much of the rest of the armour.

Sources:

http://tankarchives.blogspot.ca/2013/03/soviet-85-mm-guns-vs-tigers.html

http://tankarchives.blogspot.ca/2013/03/penetration.html

http://tankarchives.blogspot.ca/2013/03/is-2-vs-german-big-cats.html

Theoretically the D-5T gun could penetrate the Tiger, but only if it got within about 1,000 m

However, the Tiger could easily out-range the T-34-85 with it's 88 mm gun and destroy it before the Soviet crew could get in a reasonable range to shoot the Tiger from the front. Killing shots by Tigers of 2,500+ m were apparently made on the wide-open Russian steppe.

The T-34-85's D-5T gun was even actually slightly worse than the US 76 mm gun M1. The penetration table I have linked is based upon Soviet testing data and shows thus, using AP BR-365K on armor angled at 0 degrees like the front of a Tiger:

• 100 m: 117 mm
• 500 m: 110 mm
• 1,000 m: 95 mm
• 2,000 m: 65 mm

Penetration improves only about 5 mm to each stat with APCBC BR-365

APCR BR-365P could penetrate easily out past about 1,250 yards, but after that, the chance drops off sharply as APCR projectiles have very poor flight characteristics at long ranges.

For the US 76 mm gun M1, the following figures are given for armor angled at 30 degrees, firing uncapped M79 AP shot. Translated, the performance would be better than the Soviet 85 mm gun against armor angled at 0 degrees:

• 91 m (100yd): --
• 457 m (500yd): 109 mm
• 914 m (1000yd): 92 mm
• 1,371 m (2000yd): 76 mm

Translated to 0 degrees:

• 91 m (100yd): --
• 457 m (500yd): 135 mm
• 914 m (1000yd): 114 mm
• 1,371 m (2000yd): 89 mm

When firing the capped M62 APC(BC), performance decreased a bit for some reason:

• 91 m (100yd): --
• 457 m (500yd): 93 mm
• 914 m (1000yd): 88 mm
• 1,371 m (2000yd): 82 mm

Translated to 0 degrees:

• 91 m (100yd): --
• 457 m (500yd): 115 mm
• 914 m (1000yd): 109 mm
• 1,371 m (2000yd): 98 mm

The M93 HVAP projectile could go through the front of a Tiger like a hot knife through butter, easily penetrating past 2,000 yards

What is interesting is that the 76 mm gun M1 used on the Sherman tank and the 3-inch gun M7 used on the M10 tank destroyer fired the same projectiles, just from different cartridge cases. (the 76 mm gun's case had straight sides, while the 3-inch gun's case was shorter, but wider and more bullet-shaped.

Sources:

Armor penetration converter http://converteverything.com/calculators/armor_penetration.htm

Soviet 85 mm D-5T gun: http://amizaur.prv.pl/www.wargamer.org/GvA/weapons/soviet_guns7.html

US 76 mm gun M1: http://amizaur.prv.pl/www.wargamer.org/GvA/weapons/usa_guns5.html