Wm. K. Walthers, Inc. rporate Office and Store Address. 5601 West Florist Avenue. Milwaukee, WI 53218. Showroom hours: Thursday and Friday 10:00am – 4:00pm. Customer Service hours: Monday – Friday 8:00am – 4:30pm CT. To place an order by phone please call 1-800-4-TRAINS during regular business hours.