The U.S. Army's M-2 IFVs (Infantry Fighting Vehicle) fighting vehicle proved to be the workhorse of the 2003 Iraq campaign. But that came at a cost that was not anticipated. Like most armored vehicles, the M-2 runs on metal tracks that have rubber pads attached to save wear and tear on roads and give better traction. Naturally, the rubber pads, as well as the entire track, wears out. Normally, a heavily used M-2 might need a new set of tracks once a year. In 2003 there were nearly 700 M-2ss in Iraq, and many needed a new tracks every few months. A set of tracks is normally good for 1,300-1,600 kilometers of travel. To keep the M-2ss in Iraq supplied with replacement tracks, the army's only depot that refurbishes worn tracks (about 80 percent of the track is reused) has had to go from one shift a day, five days a week, to 24/7 production. Even at that, stocks worldwide were nearly depleted by the end of the year. That was one reason for the rush to get more armored Humvees over to Iraq. These don't have tracks, and are nearly as resistant to Iraqi attacks as the M-2's are. Actually, in many cases, the M-2s were used in low risk situations because they are the only combat vehicle available. Meanwhile the army had to face the fact that a larger war, calling on more of the 6,000 M-2s in U.S. service would not be practical.
By 2011 the army had decided to replace most of the M-2s with wheeled armored vehicles (Stryker, MRAPs and armored hummers). At that point the army was also undergoing a reorganization, which has included converting some mech brigades (normally using M-2s) with Stryker wheeled armored vehicles. There were proposals to equip some combat brigades with MRAPs on a permanent basis but that never happened. Thousands of MRAPS were put into storage, just in case. The Strykers and armored hummers were deemed adequate for peacetime training and the initial stages of a war. Most importantly the Strykers cost half the $2.4 million cost of an M-2 and the armored hummers were cheaper still.
The army did not give up on the M-2 and addressed many of the problems encountered in Iraq, which was the first prolonged period of combat for the M-2. The first combat for the M-2 was in 1991, but that lasted less than a week and gave the impression that all was well. In Iraq, the fighting went on for years and the M-2 got heavier. Eventually the M-2 was found to have a serious weight problem. When the vehicle first appeared in the early 1980s it weighed 25 tons. By 2006 M-2s weighed about 36 tons. The increase comes from added equipment and, especially, armor. This makes the M-2 RPG proof, but the extra weight has been hell on the M-2s most vulnerable component, the tracks it runs on. By the time 2003 rolled around, additional weight meant that a set of tracks lasted about 1,400 kilometers. But still more weight was added (more armor), and it got to the point (in 2006) where tracks had to be changed after only 700 kilometers. This meant that M-2s in combat might need several new sets of tracks a year. Changing tracks is hard, sweaty work, especially in tropical Iraq. The crews do most of the work, and they don't like it. By 2006, the army had designed a new set of tracks that was good for about 4,000 kilometers. The refurb included new tracks, as well as replacing other worn out or damaged equipment, and adding new items (usually electronics.)