Not just semi-trucks, any vehicles with aggressive tires! I was about 6 car lengths behind a girl in a Jeep Rubicon, she was texting and continuously veering off onto the right-hand shoulder, so I stayed well back, but not far enough back because she spit rock that glanced off my hood (thank you Clear Bra) and dinged my windshield.Recently replaced my windshield. Safelite would not touch it. There are no third party windshield replacements for R8 glass. They wanted to find an alternative to OEM but there were none.
Ultimately just bought the glass from the dealer ($1450 msrp paid $1100) and used the same installer the dealer uses. $400 for the install.
Two days later caught a rock behind a truck on the highway and you guessed it, small chip embedded into the glass. Glass tech came out and repaired 98% of it. If you didn't know where the knick was you wouldn't know there was one. Stay from behind semi trucks on the highway