2013 Roadstar Trike

I wanted to use the Austone Taxi Tire 175R16 on my bike. I have converted my bike into a trike with a Voyager Convertible kit. Which means that I already have Car tires being used for my rear. I just wanted to use the Austin Tires so that I have three car tires on the rear. With the Voyager Kit I retain my rear wheel as the power tire. The problem I'm having , since I tried my bike is the tire I usually run back there a Michelen Commander II wears out with only a little under 5K miles. Normally I would get 10K as a two wheel. Not anymore. I wanted to use a car tire to extend my rear Tire use thus a car tire. Has anyone else done this and what did you do to make it work. I tow a camper trailer and my trike handles that really well.