DIY solution to deadening tire noise

[artsci]

If you are switching to 20's, the ContisportContact 5p is on tirerack in 255/40/20. I think thats the one with the foam no?

I've investigated that tire. It does not appear to come with the foam plus it's wear life is dreadful. It's a high performance summer tire.

But I have found a source that makes the same foam as the Conti foam. I'll be talking to the manufacturer on Monday. It's much lighter than the other foam types I thought about a few days ago. So I haven't completely given up yet.

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Or at least Dynamat the wheel wells? I added about 4 kits of Dynamat on top of sound stage 1 to my car and it did make a noticeable difference.

Everthing I've been able to find suggests that sound deadening the wheel wells results in very modest gains that are probably not worth the money and effort.

 

[SUPRKAR]

I understand your reservations but as you might guess they won't deter me. The tire/wheel assembly is nearly 50 pounds so the foam will add a relatively small fraction in unsprung weight. I'll just use the glue that Continental uses (yes that info is available and it's a high tack brush on type) and balance the tire/wheel assembly once the foam is attached. The centrifical force of the spinning tire with the glue should help ensure that the foam stays in place.

Full speed ahead, I am right behind you, how are the camber links working for you? OK I hope.

 

[artsci]

Full speed ahead, I am right behind you, how are the camber links working for you? OK I hope.

Working great! I like the handling more with the new camber settings.

As for the tire noise I found a very informative doctoral thesis on the topic, which confirms through experimentation that as much as a 9db reduction in cabin noise can be achieved by lining the interior tread of tires. A number of different sound absorbing foams were tested and most had substantial effects. The paper was written about 10 years ago, and foam technology has since advanced. The foam I'm now thinking of testing is open cell polyimide, which has excellent sound absorbing qualities, is extremely light (.5 lbs per cubic foot), heat resistance, highly stable under adverse conditions (NASA scientists invented it and it's used in aerospace applications). I'll be talking to a manufacturer about this application after the holidays.

 

[mdevp]

Super excited about your progression with this project. This could be the best DIY upgrade yet!

 

[artsci]

It appears that Tesla is giving some serious thought to this question. Found the following research paper on tire noise co-authored by a Tesla engineer/scientist. It's an interesting read, especially for the mathematicians and engineers among us. This paper does not propose solutions. But much of the other research I've found, as well as a number of patents, indicate that foam on the interior side of the tread is the best approach.

From the abstract:

Modeling and Experimental Verification of Vibration and Noise Caused by the Cavity Modes of a Rolling Tire Under Static Loading

Z.C. Feng
Department of Mechanical and Aerospace Engineering, 2413A Lafferre Hall, University of Missouri, Columbia, MO 65211

Perry Gu
Tesla Motors, Inc., 12259 Crenshaw Blvd., Hawthorne, California, CA 90250

ABSTRACT
Tire cavity noise refers to the vehicle noise due to the excitation of the acoustic mode of a tire air cavity. Although two lowest acoustic modes are found to be sufficient to characterize the cavity dynamics, the dynamical response of these two modes is complicated by two major factors. First, the tire cavity geometry is affected by the static load applied to the tire due to vehicle weight. Second, the excitation force from the tire-road contact changes position as the tire rotates. In this paper, we first develop dynamic equations for the lowest cavity modes of a rotating tire under the static load. Based on the model, we obtain the forces transmitted to the wheel from the tire resulting from the random contact force between the tire and the road surface. The transmitted forces along the fore/aft direction and the vertical direction show two peaks at frequencies that are dependent both on the tire static load and on the vehicle speed. We also analyze the dynamic spectra of the cavity air pressure. Our results show the presence of dominant peaks in the noise spectra. We further report experimental data on spindle responses and the dynamic pressure recorded by a sensor inside a tire. The results are in satisfactory agreement with the model prediction. Our work thus provides a basic understanding for the interaction of tire cavity excitation and a tire/wheel assembly which is critical to develop strategies of mitigating the tire cavity noise in the early stage of tire/wheel design.
Keywords: tire cavity noise, acoustic modes, rotational effect, vehicle noise.

 

[artsci]

The foam shipped today. It will be applied to my new 20" Pirelli tires next week before they are mounted on the new 20" wheels. I ordered enough foam for my 21" Michelins and 19" Bridgestones so I'll be able to do some serious sound testing on all three tires and wheel sets over the next 6 - 9 months.

 

[artsci]

Update:

After ordering foam that based on my research I thought would be best, I heard from another company that I had been trying to get technical information from about using their acoustical foam products for tire applications. Bingo!

This is part of the email I received from an engineer:

Our parent company is one of the world's largest manufacturers of polyurethane foams and has extensive experience in using foams for tire applications. There has been a significant amount of time spent on research and testing that could probably help with your efforts.

I'll be talking to him today and if all goes well placing an order. I'm assuming that Rectical makes the foam for the Continental tires and those of other manufacturers as well. My plan is to test these first on my own tires. If they produce substantial road noise reduction I'll make a kit available to other Model S owners for retrofit to their own tires via DYI or a tire shop. My own tire shop said that they'f be happy to do the installation for me when they change wheels or install new tires.

Nest step is to cancel the order for the foam I made yesterday. Now that I'm dealing directly with the manufacturer of tire foam products I know I'll get the best possible foam for this application, the same foam used by the tire manufacturers.

 

[AlMc]

You are 'the man' when it comes to DIY projects and TM enhancements. I was reluctant to have my car broken down to have deadening material applied but tire noise deadening (or decreasing) sounds like a nice way to reduce noise by 9db!?! Thanks

 

[CHGolferJim]

Have you established that the green goo stuff some folks put in tires for flat prevention/healing would be useless?

 

[artsci]

Have you established that the green goo stuff some folks put in tires for flat prevention/healing would be useless?

With foam liners the mess will be a real problem.

 

[CHGolferJim]

I was thinking instead of the foam.

 

[artsci]

I was thinking instead of the foam.

It was not intended for that purpose so I suspect it does not work as well as acoustic foam specifically designed to absorb tire noise.

 

[mspohr]

How are you going to measure sound level before and after? It would be good to have some solid numbers.

 

[artsci]

How are you going to measure sound level before and after? It would be good to have some solid numbers.

Using an accurate and highly rated sound meter iphone app: SoundMeter+, which makes it possible to email a file when the readings have been taken. I used this app to measure the before and after results for the sound deadening work. It's rated nearly as well as a separate sound meter.

 

[Sogorman]

Keep us posted @artsci! I'm planning on ordering my MS 85 with just the stock 19" wheels then after delivery picking up a set of 21" rims and some quality 21" tires. This sound damping will also be a part of my upgrade!

 

[artsci]

Keep us posted @artsci! I'm planning on ordering my MS 85 with just the stock 19" wheels then after delivery picking up a set of 21" rims and some quality 21" tires. This sound damping will also be a part of my upgrade!

I'm expecting to hear back from the engineer at the Rectical U.S. subsidiary today or tomorrow. As this technology was researched and developed in the company's European divisions (it's a German company) he told me he needed to discuss this with his colleagues there. He'll then get back to me with recommendations about what should be appropriate from the line of tire foams they've developed.

 

[artsci]

Foam arrived today. I have enough to do probably 5-6 sets of tires. I'll start cutting it to size tomorrow to prepare it for installation on the tires next week. Photos and steps to follow.

 

[Sogorman]

Foam arrived today. I have enough to do probably 5-6 sets of tires. I'll start cutting it to size tomorrow to prepare it for installation on the tires next week. Photos and steps to follow.

fantastic!

 

[mdevp]

Wow, super excited to see the results!

 

[artsci]

Wow, super excited to see the results!

I'm starting with the 20" Pirelli Cinturato P7 All Season Plus, which is a pretty quiet tire to begin with. Next up will be the 21" Michelin Pilot Super Sport XL, very noisy in comparison. The foam is 1" thick with a perforated vinyl layer on top and the layer I'll add weighs less than 16 ounces. It will be glued in with gel contact cement, which I've already tested.

It's the best rated foam I could find for absorbing road noise in the 150-500 Hz range, which is the primary frequency range of the worst tire noise.

Thickness	Frequency (Hz)​
	125​	250​	500​	1K​	2K​	4K​	NRC​
1/2"	.22​	.24​	.52​	.88​	1.00​	.68​	.66​
1"	.30​	.37​	.90​	.96​	.80​	.76​	.76​
ASTM C384 Absorption Coefficient