For those of you who have these bias tires, I was wondering how long yours have lasted? Mine seem to be wearing faster than expected, a little over 1/8" over 4,000 miles. The wear seems to have slowed lately, probably because the tires have flattened out. The tread in the center of the new tires seemed domed if that makes any sense. There isn't much difference from front to rear either. Was curious if others had a similar experience?