Someone mentioned to have your alignment checked, GOOD ADVISE!!!. Also it seems from your post the issues are on your front axle. Consider that MH manufacturers are building a house upon a chassis purchased from Ford, Chevy or whomever. On our first class A we experienced an issue with a harmonic bounce in the front end at 70 mph. In the end, we discovered the weight on the front axle was improper. My suggestion is that you check the weight of your MH on each axle and make sure it is within specs. Our fix was to add another leaf spring. If you have a problem with your chassis, it would matter what brand of tire you use. Good luck and safe travels.