symphonicpoet wrote: ↑Jun 29, 2021
"It is possible to reduce tire noise significantly by using low noise tires, but manufacturers have lobbied against this for years because they're d*cks."
Subscribed. (Even if me do like car go vroom vroom.)
TANGENT: Funny, yes. And yes, auto industry lobbyists are most often d*cks for a plethora of reasons.
But this is a gross oversimplification. Auto makers don't want overly noisy tires either - for selfish reasons. They want cars that are quiet for the driver and passengers. Certainly they can and do soundproof interiors. But soundproofing is expensive and adds *a lot* of extra weight to cars. Auto makers would much rather not have to deal with that.
Making tires quieter can be done to an extent - and new tire makers have been doing just that. New tires
are uniformly quieter than older ones. Competition between manufacturers is one reason - put two otherwise-identical tires side-by-side but one makes less noise, and informed buyers will often choose the quieter one.
But to go beyond a certain point in noise reduction means making compromises elsewhere, and those compromises can legitimately impact both safety and fuel economy.
One of the reason tires are noisy is because they have tread blocks - racing slicks are much quieter at speed. But tire tread is necessary to evacuate water from under the tire when driving on wet pavement. Eliminate tread and you make it much harder to expel water from under a tire, which can dramatically increase the likelihood of a hydroplaning incident. Lessening the gaps between the tread on the tire's shoulder has the greatest noise impact on a treaded tire, but even that inhibits the ability to expel water from under the tire to the side. So go too aggressive on the noise mitigation and you make it much more possible to have an accident in the wet.
Another way to reduce tire noise is to use softer compounds. Softer tires = grippier tires, which is great for performance and safety too. However softer tires wear out much more quickly. This is why high-performance tires tend to last 20,000, even 10,000 miles or less whereas a good all-season tire can go for 40,000-80,000 miles. And soft tires also have higher rolling resistance, which means worse fuel economy, as more of your motor's energy is going to overcome the stickiness of the tires. Hybrids and electronic vehicles often have low-rolling-resistance tires for exactly that reason, and their tires are louder for it.
A final way to reduce noise is to reduce the surface area in contact with the road - make tires smaller in diameter and skinnier. Now this may be the part that is the least 'necessary' - because it's
mostly influenced by design. Bigger, fatter tires are perceived as better tires and therefore more desirable. And today's bigger cars with higher fender heights (sometimes for design's sake - see nearly every truck and SUV - but also necessary even on smaller cars to accommodate safety requirements for pedestrian impact and crumple zones) 'require' bigger tires for visual balance. But a bigger contact patch also means greater grip for a given tire composition - which is desireable for performance vehicles but also important for wet and dry evasive maneuvers - both for cornering and, critically, braking. Most drivers use >10% of a tire's available grip in day-to-day driving. But having that extra capability there in an emergency situation could mean the difference in having or avoiding an accident.
Governments can and should continue to pressure auto and tire manufactures to make quieter tires. But practically, they are much likelier to effect a positive change in noise pollution by
designing urban roads to encourage lower speeds (not just lowering speed limits) and requiring the use of asphalt with a lower noise profile.
/TANGENT
-RBB