ThermionicScott 

"Unsuitable" is a strange word to use for a configuration that works just as well as clincher tires did for eons. Obviously, if you live in an area with goat head thorns or lots of broken glass or sharp gravel, tubeless can be a big improvement. But lots of us don't, and happily ride with tubes in rims or tires that just happen to be tubeless-compatible.

jadocs

Sounds like they are the older models that are not tubeless ready, is that correct? If they were UST, I think the internal width would be 19mm but I could be wrong. If my assumption is correct and they are just clincher rims, I don't see a reason why you could not use tubeless tires...as a regular clincher with tubes. No you would not get the same benefit as running tubeless for the reasons outlined above. It would be just like running a regular clincher in that configuration. Is that what you are asking?

Iride01 

Not too old I hope, I just bought the Open Sports little over two years ago and the Open Pro's nine months ago.

I forgot that Mavic makes several different models that they call by the Open Pro name. I believe these are the Open Pro C that are still made today. They just say Open Pro on the label. Didn't have my glasses with me so I couldn't see the very fine print that might have had a part number or such. Similar for the Open Sports.

Both are marked 622 x 15C. I'm thinking C is for clincher. I'm not wanting to go tubeless. I just wanted to know if there was anything physically different about a tire marketed as tubeless that made using them with a tube any worse than using a tube with any other tire.

So far it seems the term is more important to those that are tubeless, than it is for those of us still using tubes. Though there are some minor points that were brought up.

ThermionicScott 

In this context, the "C" stands for "crochet" meaning that it's a hooked rim.