Terry P.

The 18" wheel/tire combination is interesting in that it is the same overall diameter as the 17" combination. In the 18" setup, Lexus uses a lower profile tire, 55 series vs 65 series to achieve the same result. Must be marketing again. In researching this more, it appears that the 55 series tire may also be hurting ride and comfort as it has a smaller sidewall and is more for sports performance. You are correct about the dB vs dBm, I usually measure audio level in a broadcast system. I have a handheld audio meter and driving down the freeway at 60 mph on concrete gives me the 90 dB reading. I am using "C weighted" and fast response. However, the final result is that at freeway speeds, it is a little difficult to carry on a conversation. Btw, the 96 Tahoe with 160K miles is a little quieter, but I think the issue here is mostly the tires.

I recently purchased a 2006 RX330 and an surprized as to how rough the ride is and how noisy the vehicle is at 60 mph. The vehicle came with 18" rims and mud/snow tires. The ride is firm, but you can feel each bump and is more pronounced on a rough concrete roads. On the freeway, where I do most of my driving, I am reading more than 90 Dbm of noise. Has anyone else with a new RX330 experienced these issues or od I have to live it?