This is a common issue for folks in the 250lbs range. I am 235 and cannot expect factory wheels to last more than a season. I worked in bike shops for 40 years and have seen this over and over again. The only real long term solution is to have a wheel built with high quality name brand hub, rim and spokes. It ain't cheap, but does result in a wheel that will go the distance. Please do yourself a favor and bite the bullet now on a quality custom built wheel.