I also weigh over 300lbs. 36 spoked rims that are wider and high flange hubs will solve your problems. Availability of parts can get in the way. I recently purchased ebikes for me and the wife. Prior to purchase I contacted the manufacture and was told that the wheels were the weak point. I am replacing both front wheels. Velo Orange high flange front hubs. Ryde Andra 40 rims. Sapim spokes. I purchased belt drive ebikes so the rims and spokes is all I need for the rear. The Ryde Andra rims are as tough as it gets.