My 2008 HCH II has 29000 miles but its rear OEM tires cupped inside and worn out really bad. Is this some thing due to bad alignment or too much load? I am keeping tire pressure 40 psi front and 38 psi rear and usually carry 5 person including 3 under 14 children in the back with some stuff in the trunk weigh not more than 200 lbs. Any suggestion on how to correct this will be greatly appreciated. I know for sure, I have to replace those 2 tires. Would rear wheel alignment help?