I've an '87 300TD, fine car, but has worn off the inside thread of both back tires. 6/32 on the outside, 6/32 all around on both front tires, bare metal threads on the inside of both back one. I watch load weight and never exceed, not even close. I was told this car has a 'hydraulic' suspension. How do I diagnose it???? Anything else that may be a contributor??