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Discussion in 'Model S: Driving Dynamics' started by artsci, Nov 23, 2014.
Even a subjective guess before vs. after says this is an amazing difference!
Great news David.
I hope I get the same results with my foam lined 21" Michelin Pilot Sort. They go on my car Friday. These are the same tires I did sound testing with before I shipped them to Belgium to be lined with foam. So by the weekend I'll have before and after readings.
That's fantastic news! Thanks for sharing your results!
Perhaps I should point out that it will take quite a while to have a good understanding of the effects of the foam treatment.
Several issues I've thought of:
1) Tire life. Will the foam heat the tires and drastically reduce the tire life? Or, conversely, will it improve tire life by reducing vibration? It will take months, possibly almost two years, before I'll have the results of just testing 1 set of tires!
2) Life of the noise reduction. Will the excellent results I've experienced last? Or, as the tires age, will the foam break down & stop working? Worse yet, if bits of foam break loose, I could actually experience an increase in noise!
3) Range reduction. I'm positive there will be some negative impact on range. With time, I should have a fair idea of the added energy consumption levels, but I've not done the careful measuring needed to get a true picture.
1) According to Continental, their ContiSilent foamed tires perform exactly the same as those without foam. I would not expect a measurable tire life difference.
2) Foam breakdown might be expected more in low mileage cars that take longer to to wear out the tread, thereby allowing more time for oxidation to do its work on the foam. Would that be an argument for filling the tires with pure nitrogen instead of air? As to foam breaking up, I would guess that has been thoroughly tested by the manufacturer from the outset.
3) What makes you expect a range reduction? Certainly not weight; isn't the stuff only about 16oz? Did it feel stiff enough that you think it might interfere with flexing of the tread? But Conti tests say that there is no change in performance, so it couldn't affect flexing..
What I would be more concerned about would be what happens if you should have a flat tire. How badly would the foam be damaged? How would that affect repair of a puncture?
Good questions. I hope the claims are correct, but I still think they should be tested.
Weight, and possible air convections inside the tire, might cause range reduction. Especially if I do a lot of stop-and-go travel. I doubt there will be much difference if I travel at a steady speed.
Interesting question about having a flat tire. I did not think about that possibility. I do carry a tire repair kit, as well as a tire slime kit, in my car. So far, in almost two years, I have not needed to repair a tire. My last car, however, I needed to repair a tire almost every half year!
Slime would probably be bad with the foam, would be much harder to clean out for a full repair (would probably still work, but the tire would likely be irreparable after that)
As for the patch kit, I see no reason that would change. (though it could be a problem for a professional patch done by a tire shop from the interior of the tire, though it seems to me that it should be able to be overcome if the shop can get their hands on a small chunk of the foam to place back over the patched area.)
Following the latest posts here, information from Recital indicates that the foam will not break down and tire performance will not be affected. Were talking ounces not pounds for the foam.
BTW, here are a few photos of the foam in my 21" Michelin Pilot Sports, which go on the car Friday for testing.
There are two layers. The first is about 1/2" thick and its for heat control. The second is about 3/4" thick and it's the acoustic foam.
In fact, any liquid inserted into the tire for patch repair would likely be unevenly absorbed by the foam in a sealed environment where it would never dry out, completely throwing the balance of the tires off. When using the DIY patch repair kit, you would need to be sensitive to the fact that the foam is there so you don't tear it up roughing up and patching the hole, but you'd certainly want to use a portable compressor rather than anything that comes in a spray bottle to re-inflate.
As for air convections within the tire, I don't see how that would change. The air is going to be spinning around with the tire and I can't imaging the foam will have much impact on that. The point of compression is continually changing as the tire spins, but I would expect the foam to actually absorb some of those forces and improve the environment inside the tire.
I'm not sure if anyone has modeled the turbulence inside a rolling tire, and I'm sure nobody has successfully done real-life measurements, so we have to resort to guessing. My guess is that the foam will dramatically increase the turbulence. That, in turn will heat the air. Will the energy wasted by creating that heat make any difference? Probably not, but time will tell. Will the extra heat generated make any difference, compared to all the heat generated by the continuously flexing tires & the heat generated by the tire/road friction? Again, probably not, but time will tell.
Fobo Tire reports the heat of each tire real time, so I'll be able to measure the impact of the foam on tire heat. I don't think it will be much but we'll see. I'm really not concerned about this as I'm sure Recticel has evaluated all of these factors in their design of the foam and its application.
Excited about this thread, thank you for all the hard work. I wonder why no other high end autos who pride themselves on having the quietest cabin haven't pushed for this earlier from tire companies. It seems pretty intuitive and I would imagine that heat resilient acoustic foam has probably been around for awhile.
...makes me wonder if we just need a proper high-temp adhesive and about 10 tire-wide strips of Dynaliner (or similar acoustic foam) to DIY this. I must be missing something as it can't be that simple......?
I've thought about this question and what I've concluded is that this solution is most appropriate for an electric car. Even quieter ICE's generate considerable engine, gear, transmission, etc noise under power surges. A Tesla has almost none of that so the road noise becomes a much bigger issue at all speeds, torque, motor speed levels. The tire foam business will grow as electric car sales grow.
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If it were that simple tire foam kits would already exist.
My goal, after our tests demonstrate that this works as expected, is to have Recticel sell DYI foam and adhesive kits in bulk for we Telsa owners. The adhesive they use has a bluish color so it's not the standard contact cement I expected. If Recticel won't provide kits to us I may develop my own, but not after some major experimentation with foam materials and adhesives. Remember, this all started when I contacted a acoustic foam companies to ask about foams appropriate for this application. None had answers expect the company that was a U.S. subsidiary of Recticel, who then referred me to the Belgium HQ.
This, plus the fact that in traditional ICEs, the tire noise would likely get drowned out by the engine noise many times. As such, its a better "value" to do more soundproofing for all outside noises vs. muffling tire noise. So their efforts have been focused more on quieting the cabin from the exterior versus tackling specific factors of the exterior.
Woot! Go artsci, go! And thank you for the explanations. On a side note, I think its just incredible that such a ground-breaking car such as the MS could help potentially create a new sub-industry, acoustic dampening tires. It's just so fascinating to me.
Subscribed. I don't mind my road noise very much, but I'm really excited to see how this turns out!
I never minded it until it became the only thing I hear. Tesla's are just so frickin' quiet otherwise... :biggrin:
Think of us poor saps on the Goodyear tires! At least your cars have the Michelins which are much quieter!
Correct and good thought!