Niether of mine are heavy at all and I have larger
tires (84 m635 8 1/2&x17 85 8x17 635) wheels and tires are usually the issue but the PS belt may be too loose as well. 50% chance the streeing mount bracket is broken. Everyone of my 35 or 40 5ers and 6ers have either cracked or broken off, displaying a verity of different problems. Try the Home Depot fix first to see. You can't usually visibly tell unless you are under the car and someone turns the wheel for you hard left the hard right. Good luck.