Are sunbeds good for rheumatoid arthritis?

No, Rheumatoid Arthritis is an Autoimmune disease and to date no way has been found to stop the immune system from rejecting tissue that it should leave alone. Sun beds may introduce some vitamin D into the system but that has nothing to do with controlling the damage done by RA. add to that the very real risk of melanoma formation in the skin which can easily spread from there to any other part of the body and you are playing with death rather then the alleviation of pain.

Sunbeds aren't good for any condition. They are dangerous and increase the risk of melanoma. Not a good idea. If you need Vitamin D, eat foods rich in Vitamin D such as yogurt, mushrooms, fish, etc. or get some actual sunlight for 15 minutes a day or take a Vitamin D supplement. Rheumatoid arthritis has many other treatments to consider.