You are going to have to take some clearance measurements with your 145/R12 Radial Trailer Tire # AM35354 to determine if the larger Kenda Karrier ST175/80R13 Radial Trailer Tire with 13" Black Mod Wheel # AM31990 is going to fit. The 175/80-13 is 2.8" taller and 1.3" wider. For vertical clearance we like to see at least 3" for the suspension to travel so with the height difference you will want to see at least 4.4" with your current tires. Remember to check the vertical clearance around... view full answer...