19" vs 18" Road Noise Comparison

[Whacker]

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.

 

[Dangerous Fish]

You don't mention tyres, only wheels. What tyres did you use for each test? If they not the same type with similar amount of tread then it's hardly a useful comparison.

 

[DirtyT3sla]

I did this comparison as well with stock wheels and tires 18 vs 19. I took an average over about 5 miles for each tire, over 2 different roads. One at 75mph, one at 60mph. The ride is definitely smoother in the 18s. I could tell immediately. And the sound seems quieter. Maybe what you're saying about the "tone" is why it felt so much better, but the dB wasn't that different (61dB for 18s, 63dB for 19s). I also measured with my phone, which is not very accurate tbf.

I also measured efficiency. I used TeslaFi to compare drives of the same exact route, with similar temperatures, and total drive times (so average speed was the same) and I found the 18s with caps to be around 5% more efficient, although the difference was not statistically significant.

I also prefer the look of the 18s, with or without caps

I made a video about it here if you care to see:

 

[Whacker]

That's nice work, Dirty. Great resource. Your video came out after I'd made the decision to switch- I wish it had been out last year when I was ordering!

While the phone apps aren't necessarily accurate, we can expect them to be precise and reproducible. We can say that my 18s are significantly quieter than my 19s, we just can't compare between phones and say your 18s are quieter than my 18s, etc.

I'm definitely enjoying the ride more, but I can never agree with you that the 18s look better . They look very nice with your gray but clash with the dark blue paint on my car.

 

[lhrmeonom]

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:

View attachment 442407

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.

To be fair, the model 3 is meant to be the Tesla equivalent of the BMW 3 series, which has a lot more road noise (from my experience) than the 5 series.