Thanks, I have checked out Peter White's site many times, and while it's full of great info it's somewhat inconclusive with regards to rim width/tire width concerns, and really I suppose I should just call them.
I just hoped to find someone with the same set up who could advise on any pitfalls regarding their success or failures.
I should have mentioned they are the 35mm Nokian W106.
The Nokians W106 35mm mounted easily and are performing very well on the MA-3 rims. Performance-wise they're amazing on the ice and hardpack. It's really fun and it's less stressful to be able to ride with a measure of confidence. I gotta say though, I ride a single speed, and the performance/speed hit on dry pavement is major, they are loud and slow. But the trade off is safety and confidence and it has turned my commute back into workout.