Here's my 2 cents.
Bought my 06 LC 3years ago. It had aging Bridgestone Duelers. It seemed OK on the highway, but I was not paying noise that much attention then.
I replaced them with BFG KO's in 2 weeks. It was much quieter. I was surprised by how quiet the KO's were.
So, tires make a big difference. Quieter than my 07 Honda CR-v ( which is known for road noise).
So quiet it was very relaxing on the highway.
I just recently replaced the Honda tires with Michelin Defenders ( had Michelin Latitudes with 40,000) and it is much quieter.
FWIW the Defenders are very nice road tires.
Also improper windshield installation can cause wind noise as noted in many threads here.
Tires are a major factor, but the LC can be very quiet on the highway.