Date: 7/8/2008 9:38 pm EDT
Hold on a minute Nancy.
Your floor is a wood structure! Are the floor joists 16" deep or do you mean the floor joists are 16" on center?
It sounds as if your current vinyl tile is experiencing deflection between the floor joists. This would indicate that your subfloor may be inadequate for the tile installation you now have. The minimum thickness of a subfloor required by code is usually 5/8" thick. It isn't unusual for builders to take advantage of that minimum to save money. The truth is...a minimum thickness subfloor doesn't always qualify for certain flooring materials.
A rigid floor product such as Avaire tile may not do you service if the subfloor is deflecting. Even tho Avaire tile is much thicker than what you have now it is also very rigid and brittle and a person in a wheelchair would be delivering a tremendous point-load to the subfloor.
There is also an overall deflection requirement for tile installations of a maximum deflection of 1/360. It is not known at this time whether or not your structure meets that minimum. It sounds as if it may not.
It would be helpful to know the following:
What size are the floor joists?
What is the spacing of the floor joists?
What is the unsupported span of the floor joists?
What is the thickness of the subfloor?
What is the subfloor material used?
Knowing the answers to the above questions your deflection abilities of your floor can be determined and a suitable floor covering can then be recommended.
Not trying to discourage you using Avaire tile but at the same time not wanting you to experience another flooring failure.
Laminate flooring has a very high tolerance for deflection and if the joints aren't separating that may be your better choice.