N Scale Peco Code 55 Track - Model Railroader Magazine

As others have noted, the issue is with Atlas Code 55, not PECO Code 55 (which is actually taller rail partially buried in the ties).

The Atlas C55 problems are with older high-profile ("pizza cutter") wheels that have extra-deep flanges. Current Micro-Trains releases have mid-profile wheels which work fine with either track.

Older M-T wheels can also easily be replaced with mid- or low-profile wheels.

Some older engines also have deep-flanged wheels and may also bump along Atlas C55 track. Replacing these wheels is more difficult.