The M48 is notable for the odd shape of its lower and frontal hull, it being curved and boat-like. The use of steel armor on U.S. tanks reached its apex in the 1950s and 1960s; the last U.S. tank to use sheer thickness of steel plate as its primary means of protection was the M60. Similar to other U.S. tanks of the time, the M48 displayed a near-complete lack of sponsons, the upper run of tracks being essentially level with the hull top.
The M48 and T-55 offered similar levels of armor protection; the M48 was superior in some areas, the T-55 in others. All angles are from the vertical; I have rounded the values to the tenths place.
M48:
| Area | Actual Thickness | Effective Thickness |
|---|---|---|
| Lower hull front | Curved, two plates; 102 mm @ 35°, and 38-102 mm @ 53° | 63.1-169.5 mm |
| Lower hull sides | Curved; the majority being 90 mm @ 35° | ~109.9 mm |
| Lower hull rear | Two plates; 25 mm @ 60° and 35 mm @ 30° | 40.4-50 mm |
| Hull floor | 13-38 mm @ 90° | 13-38 mm |
| Upper hull front (glacis) | Curved, 110 mm @ 60° | 220 mm |
| Upper hull sides | N/A | N/A |
| Upper hull rear (exhaust grille) | ~25.4 mm @ 0° | ~25.4 mm |
| Hull roof | 45-57 mm @ 90° | 45-57 mm |
| Turret front | Curved, 25-178 mm @ 20-50° | 38.9-205.5 mm |
| Gun mantlet | Curved, 114 mm @ 30° | 131.6 mm |
| Turret sides | Curved, 65-115 mm @ 28-33° | 77.5-130.3 mm |
| Turret rear | Curved, 25-51 mm @ 20-90° | 25-54.3 mm |
| Turret roof | 25 mm @ 90° | 25 mm |
T-55:
| Area | Actual Thickness | Effective Thickness |
|---|---|---|
| Lower hull front | 100 mm @ 50° | 174.3 mm |
| Lower hull sides | 80 mm @ 0° | 80 mm |
| Lower hull rear | 20 mm @ 70° | 58.5 mm |
| Hull floor | 20 mm @ 90° | 20 mm |
| Upper hull front (glacis) | 100 mm @ 60° | 200 mm |
| Upper hull sides | N/A | N/A |
| Upper hull rear | 45 mm @ 17° | 47 mm |
| Hull roof | 15-30 mm @ 90° | 15-30 mm |
| Turret front | Curved, 70-200 mm @ 0-52° | 113.7-200 mm |
| Gun mantlet | N/A | N/A |
| Turret sides | Curved, 115-160 mm @ 0-45° | 160-162.6 mm |
| Turret rear | Curved; 65 mm @ 0-45° | 65-91.9 mm |
| Turret roof | 30 mm @ 85° | 30.1 mm |
Effective Thickness Comparison:
| Area | M48 | T-55 | Advantage |
|---|---|---|---|
| Lower hull front | 63.1-169.5 mm | 174.3 mm | T-55 |
| Lower hull sides | 109.9 mm | 80 mm | M48 |
| Lower hull rear | 40.4-50 mm | 58.5 mm | T-55 |
| Hull floor | 13-38 mm | 20 mm | M48 |
| Upper hull front (glacis) | 220 mm | 200 mm | M48 |
| Upper hull sides | N/A | N/A | None |
| Upper hull rear | ~25.4 mm | 47 mm | T-55 |
| Hull roof | 45-57 mm | 15-30 mm | M48 |
| Turret front | 38.9-205.5 mm | 113.7-200 mm | Draw |
| Gun mantlet | 131.6 mm | N/A | M48 |
| Turret sides | 77.5-130.3 mm | 160-162.6 mm | T-55 |
| Turret rear | 25-54.3 mm | 65-91.9 mm | T-55 |
| Turret roof | 25 mm | 30.1 mm | T-55 |
Sources:
90 mm Gun Tank M48 Patton (M48-M48A5 Patton), citing;
Hunnicutt, R.P. Patton: A History of the American Main Battle Tank, volume 1. Navato, CA: Presidio Press, 1984.
Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
Miller, David. The Illustrated Directory of Tanks of the World. Osceola, WI: MBI Publishing Co., 2000.
Decker, Oscar C. "The Patton Tanks: The Cold War Learning Series." Camp Colt to Desert Storm: The History of U.S. Armored Forces. Eds. George F. Hofmann, Donn A. Starry. USA: University Press of Kentucky, 1999.
Foss, Chris. Modern Tanks. Glasgow: HarperCollins Publishers, 1995.
Myszka, John. Israeli Military Vehicles: The First 50 Years. Australia: Mouse House Enterprises, 1998.