The Panaracer Pasela TourGard (or TG) comes in widths fromj 25 to 35. Has some tread, however. Kevlar belted, natural sidewalls. Harris has them in folding model for the 28, 32 and 35 widths. Recessionary pricing. Continental GatorSkins have less tread, but brown walls, and I don't think they're available in 32 mm width.
I liked both the Specialized Turbo and the Avocet slick tires. I wonder if Avocet will ever produce theirs again (though they had already converted to blackwall).