A well-constructed mystery, guaranteed not to disappoint Sandra Brown fans, or any mystery readers.
BUT (spoilers ahead)
First, in the 21st century, I find it unconvincing for murder and mayhem to be motivated by the desire of a gay person to stay in the closet, even in Charleston, SC. The people of Charleston should be offended that anyone would suggest otherwise.
Second, valve caps are not required to keep tires inflated.
Even if they try, their tires will go flat before they can catch us. ... She opened her fist ... on it lay four valve caps.