I am considering the purchase of a quality set of studded tires for occasional use during icy periods (a couple of weeks per year tops). They will not be used often, but they will allow me to continue my daily rides and run my errands even during those annoying icy patches.

I can put the tires on my 26" mountain bike, which will require the addition of fenders, or on my 20" dahon which already has fenders and is my goto bike for errands. My question for those of you who have used such tires on both types of bikes, is there one or the other that has superior performance/safety on the ice or is it a wash?

havent used ice tires on my full size bike.... I have on my 20 inch Dahon ...
I woudnt use the mtb as it feels bigger and the "lower" more open feel of the folding bike make me feel safer in touchy situations.

the tires sizzle like hot oil in a frying pan on dry roads, but are unreal on the ice.... I bet you are looking for that black ice when u have those tires...
( just be carefull when stopping your feet will slip away !!!... )

Bike Friday also makes a front-fork ski

What applies to 20" vs. 26" studded tires in regards to performance is the same for non-studded tires. As to safety, they will have the same grip on ice. At the same time I agree with brakemeister - on a 20" folding bike you feel safer, due to the "lower and open feel" of it. If you wipe out, the chance of getting entagled in the frame is much lower. Also, acceleration and agility will be better on the folder, which can come handy when you need to avoid some stuff. I have Schwalbe Winters for my Dahon and used them last winter. They work great, though they are slow (but they would be slow on a big bike, too). I had a good spill on my Dahon on ice (though I didn't have the Winters on at that time), and was glad there was no top tube to deal with :-).

Thank you'll. That is what I was looking for. You'll confirmed by suspician, that yes I would "feel" safer on the Dahon...

Thor, do you keep the studded tires on your site in stock?

Studded 20" tires work just as well on ice as studded 26" tires. In other words, astronomically better than non-studded tires of either size.