Not necessarily. CJTF76 here in Afgh has suffered several serious IED attacks on convoys, all of which contained wheeled vehicles. The only "armour" the US has here are the U/A HMMVWs. At least two of these have been destroyed by IEDs while I have been here, with fatal results. IEDs have been rigged in the Mideast that have killed MBTs (Merkava and, IIRC, M1). No type of vehicle is really "proof" against IEDs if the bombers can access enough HE.
The M113 will probably be relatively OK if it has lots of armour, but its flat slab sides and flat bottom traditionally rendered it vulnerable to attack by several different means. Hopefully the combination of add-on kits of various will keep the US soldiers safe. Cheers.