I think both view points have made their case.
^ I think that's really the short and long of it, where it comes to aftermarket siping. My understanding is also what you'd read,
GaryInMI - that the NSC asked for removal of the citation. And as for the 1988-dated NHTSA "interpretation," I unfortunately really am not sure what that means...my understanding of their Interpretations are used to help requestors clarify the laws/codes/ordinances. In this particular letter, it seems to just be a compilation of various citations (of varying applicability to road-legal vehicles) and testimonials.
SikPro3, is there a way for you to test 10/10th straight-line braking in clear, clear-wet, and snow/ice conditions?
While we won't have anything to compare the data to (unless you've got another set of factory tires available for back-to-back runs), at least we can get an idea of what we're looking at.
The bigger problem with this is that there is always a chance for tire damage (both accrued as well as acute), as you'll need to engage ABS from a reasonable road speed (i.e. fast enough to elicit ABS intervention for a long enough distance so as to make a difference in the data)....finding a safe area to do test in this manner, with a consistent surface, is yet another concern, particularly as you'll need to set up braking marker as well as measure distance-to-stop. Consistency (i.e. vehicle weight/weight distribution, etc.) will also need to be taken into account.
Perhaps more easily obtained would be straight-line acceleration numbers?
Regardless, even though you'd be gathering but a singular data point, it'd be an
interesting data point. The possibility of being able to track changes in your observations as the tires wear through the sipes will also be very, very interesting.
I think that more than likely there will be clear improvements in straight-line acceleration in powder snow. Even with modern winter tires, tire engineers continue to credit tread design as the major contributing factor, here. Other areas of performance I'm less willing to bet on, as confounding factors are likely to come into play that, in my humble opinion (tire science is way beyond the scope of my comprehension as a simple hobbyist), can potentially sway the results more than this lone variable otherwise should.
It's really too bad that there's not more rigorous and more modern testing of siped tires available. Instrumented tests of both straight-line performance as well as skid-pad would be most interesting, to say the least of tests conducted by true professional test-drivers. Having been lucky enough to have gotten a taste of that - both in terms of being able to do some of the testing myself (while being yelled at by the instructor to "go faster/harder" so that the true limits of the tires can be probed

) as well as being able to ride shotgun while the manufacturers' test-driver hot-lapped on a race-track - it makes me hunger for that kind of data.
