The rims on my MTB/Commuter are 18mm and were originally fitted with 2.0 tyres. I fitted a Ritchey1.0 on the front and 1.4 on the back wheel and have had no problems in thousands of miles. For the price, I think they are a good tyre. When I fitted them I initially thought the sidewall was a bit thin and didn't expect much from them to be honest.
Happily, my initial impression was wrong, and they have been, in my experience, a durable tyre. I've been doing 100-150 miles a week for around a year or so with no flats or cuts or problems of any kind. Fitting the Ritcheys has given me the most "bang for the buck" of any performance upgrade. When they need replacing, I'll be fitting them again.
P.S. The rims on my road bike are wider (20mm) and have narrower tyres (23c), again without problems.