So I have a Kona Ute I got sometime around 2011, and last year I installed a BionX motor on it. While I love what this bike can do, my rear innertube doesn't seem so happy with the arrangement. My rear innertube has failed twice in the last month, and once only a few months prior. As far as I can tell, going up and down curbs seems to be what ultimately caused the failure the last couple times. Does anyone know if there's a particularly robust kind of innertube I could throw on the back wheel that would hold up to the heavier stresses I'm putting on the back wheel? Or is there some trick to managing tire pressure for heavier bikes that I'm unaware of? The bike itself is 55lbs and I try to keep the pressure between 50 and 60 PSI, and the max pressure listed on the tire is 75PSI. I've checked the inside of the tire, and the inside of the wheel itself where the innertube rests, and couldn't find anything that could cause an issue with the innertube.

Any advice is appreciated! Thanks.