I read with great interest the article on tire noise in the July issue of TTI.
I believe that tire noise in particular, and vehicle noise in general, is going to be an extremely important issue in any future validation of a vehicle. Decibel levels are already hazardous in more congested areas.
Tire noise at high speeds has not been reduced enough. In fact, in some tests that Pelmar Group has conducted, the noise level has increased, especially from tires produced in the East. This is true for both PCR and TBR tires. I am not aware of any tests conducted with off-highway and agricultural tires, but I believe this will be the next step due to the increased demands placed on these tires.
A speed of 100 km/h is not unusual as has been in the past for any off-highway tires. Larger tires are now required to behave like truck tires, which are meant to drive on highways. This necessitates special features and specifications, which have traditionally not been required of off-highway tires. For example uniformity testing, low spot and harmonic tests.
Research conducted in Paris, France by a group from Heidelberg University in Germany measured the noise levels of traffic in general, and of individual vehicles in Paris, France. Although I have not seen the final report, the interim results clearly indicated that the highest noise pollution in Paris is produced by scooters and motorcycles, not buses, trucks or cars. The margin was very high by any comparison.
It was also mentioned in this interim report that despite there being existing laws addressing noise pollution by vehicles, the authorities are not implementing them properly.
Generally speaking, while tire noise level is very important, there are other high decibel noises created by other elements of a vehicle or different vehicles, which needs to be addressed either first, or simultaneously.