In 2010 my wife wanted me to trike my Goldwing and I did. My wife passed away 2 and 1/2 years ago and I kept this trike but I was able to sell it and tomorrow I will pick up another Goldwing. I ran a car tire on the back and forgot what size that will fit. The new to me is a 2013 so what size is the best for this bike. I want a run flat any help will be greatly welcome.