It's true that they weakened the wording in that section of the body, but the description of the actual research does make it sound like the factor of 1,000 was a typical case, not the worst case:
> Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles.
>
> Compared with regulated exhaust emission limits of 4.5 milligrams per kilometer, the completely unregulated tyre wear emission is higher by a factor of over 1,000.
Of course, this assumes that the tyre particles captured by their methodology are (on average) equally bad as exhaust particles, and maybe brand-new tyres wear especially quickly or something. It does seem hard to square the factor of 1000 from this study with the estimate that non-exhaust emissions account for a mere 60% (rather than 99.9%) of PM2.5 emissions.
Would be curious to hear from anyone who understands emissions testing better.
Life of car tyre is ~40e3 km. 5.8g * 40e3km = 232 kg. Or 58 kg per tyre. A new tyre weighs about 8kg. I guess it might loose 3kg. So I think they've over estimated by about 20x.
Keep in mind too that a tire that has no usable tread life left is still quite heavy compared to the full tread life, new, version because there is so much left for the sidewall and the steel belts inside of the tire. They must be getting this number from measuring something else in addition to the tire
> Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles. > > Compared with regulated exhaust emission limits of 4.5 milligrams per kilometer, the completely unregulated tyre wear emission is higher by a factor of over 1,000.
Of course, this assumes that the tyre particles captured by their methodology are (on average) equally bad as exhaust particles, and maybe brand-new tyres wear especially quickly or something. It does seem hard to square the factor of 1000 from this study with the estimate that non-exhaust emissions account for a mere 60% (rather than 99.9%) of PM2.5 emissions.
Would be curious to hear from anyone who understands emissions testing better.