only front wheel there's no 15 inch radial tires for the stock rear wheel . you have to get an aftermarket wheel in a 17 or 18 inch which i have few if interested
did you sync your carbs after install ? you might just a lean pop maybe correct with a little turn af screw till it stops ... also check for carb boots leaking sucking air . I use a unlit propane torch and go around boots see if idle changes
I had near the same issue I switched to lithium and crank faster and started up faster . Another issue I heard was the inside the starter it's gets very dirty and needs to be cleaned