Sorry, I searched with Google for the two tires you described and couldn't find any info. Where are you getting them from? An internet dealer or local dealer?
Are you getting new wheels also? You would be less likely to disturb lawns if you use a wider turf tire (less PSI because of the wider footprint). If you are buying another set of wheels, maybe purchase a 12" wide wheel (your current wheels should be 9.75" wide) and get some 33x15.50.16.5 turf and sand tires. You should be able to get these from Bobcat or Galaxy Tire (http://www.galaxytire.com/pages/ProductDetail.asp?product_id=614&cat_id=1). The downside is that you will lose some mud performance, but if you have your original wheels and tires, you could switch back if necessary for muddy jobs.
Foam filling the tires will add weight. This is good for added ballast and increasing your lift capability, but will increase your machine weight. If you increase your machine weight without going to a wider tire, you will most like rut up lawns more. Are aircraft tires smooth tread or just grooved? I imagine a turf tire will give you better performance than an aircraft tire. I also don't know the load ratings for aircraft tire sizes that would fit your machine.