Vascular dilator systems, kits, and methods allowing for sheathless introduction of a treatment device into a body vessel or body cavity are disclosed. A vascular dilator system can include a dilator assembly, including a tubular shaft and a deformable member, and optionally, the treatment device. The deformable member can include a non-biodegradable material and can have a diameter at a proximal end portion that is greater than a diameter at a distal end portion. The distal end portion of the deformable member can be coupled to an outer surface of the tubular shaft, at or near a shaft distal end portion. The proximal end portion of the deformable member can include a diameter configured to receive or stretch around a distal end portion of the treatment device. In use, the deformable member can provide a tapered bridge between the outer surface of the tubular shaft and an outer surface of the treatment device.
