The road noise in my M3 is driving me crazy. I can’t use the speakerphone, I have to crank up podcasts to shouting volume, and I feel worn-out by the noise on long trips. I traded a BMW 5 series for the M3 and the contrast is stark. The only car I remember being louder was a rental Subaru. I have no problem with wind noise, only the noise from the tires when I’m on anything less than perfect new asphalt. I’d chosen the 19” wheels for looks, but after a year of living with the noise I began to wonder if the 18” wheels would produce less noise and make the car more tolerable. So I found a set and gave them a spin, testing road noise with each set as well as some comparison vehicles I had available. I kept conditions as constant as possible and there was no nearby traffic. Readings were obtained from the same sections of road after reaching a steady speed. Tires were cold and each had about 5k miles of wear, inflated to 42 psi. Fan at 3. I used Decibel X Pro, A-weighted, on my iPhone. The phone was resting on the center console arm rest in each vehicle. Temperature differed slightly with each test: 76F for 19”, 72 for 18”, 67 for the Silverado, and 74 for the Enclave. Results: Road A: Smooth asphalt, 25 mph Road B: Smooth asphalt, 60 mph Road C: Concrete with expansion joints, 60 mph Subjectively, the noise of the 18” wheels is more tolerable; it seems to be lower-pitched and less intrusive. It’s still really loud. I realize the M3 is no German sports sedan, but I would gladly trade a little bit of range for a more acoustically bearable ride. I find the ride more comfortable with the 18” wheels, with better absorption of small bumps. I don’t really engage in “performance driving,” but I have felt the 18s slip a few times on rapid acceleration on rough pavement, where I hadn’t noticed this with the 19s. I think I’ll drive on the 18s for now. I plan to try the DIY door seal additions eventually and will see if I can replicate the improvements reported by others.