I have both varieties of the Vredestein tires that Ron posted pictures of in the previous post.
I put a set of the Quatrac 5 tires (fronts and rear) on my 2009 GS. Noticed a big improvement in the ride and handling seems crisper as well. Not enough miles to see how they wear over time but expecting reasonable wear, even on the rear tire. Great tires so far!
I purchased a 2021 RTL this March and have managed to put 7000 miles on it this year. Front tires still look like new, while the rear is ready for replacement with barely any tread showing in the center...and very little wear on the outer sections. But this is expected for the stock Kenda rear tire. The OEM Kenda did the same on the rear of the much lighter 2009 GS. I got maybe 8000 miles from the Kenda on the back of the GS. Note that most of my riding is on rural blacktop and chip and seal raods. The chip and seal is much harder on tires than good asphalt or concrete with significantly faster wear. See the same on my Ducati as a top shelf sport touring rear tire is shot in about 7-8K miles as well.
Last fall I started to shop for a set of Quatrac 5 tires to have on hand for the RTL...but by then they were all gone in the sizes needed for the Spyders. I ended up getting a set of the new, directional Quatracs for the RTL but haven't gotten around to changing them yet. I like the looks and expect the directional Qutrac to perform well. I bought a second Quatrac for the rear, just to have an extra if needed. In any case, based on the three tires I have worn out on the 2009 GS, the rear tires wears much faster than the front, and when the option to buy an extra rear presented itself, I picked up an extra as a hedge for supply shortages later.
My biggest reason to purchase the Quatrac 5, or later it's replacement, the Quatrac was that they are a sports touring, all season automotive tire with the Mountain Snowflake, Severe Snow Rating. These type of tires have a softer rubber compound with lots of small sipes for good traction in snow (not that I plan on riding in the snow!!) and very good wet traction with the many channels to move the water away from the contact patch effectively. Both of these tires have the same Severe Snow Rating and both have the UTQC rating of 400AA, or, a Treadwear rating of "400", a Traction rating of "A", and a Temperature rating of "A". In general terms this translate to a softer tire with good traction in wet and snow, but one that isn't expected to wear as long as a "600" rated tire such as the often cited General Ultimax RT43 for rear tire use. Note that there have been several posts of the Ultimax being "easier to spin" than the stock tire, especially as tread wear increases. This is often the case with a harder tire more biased to tread life at some expense of traction.
While I don't intend to go out in the snow (that would be a disaster on the Spyders), I feel that either of the Quatracs will give exceptional wet traction if I get caught out in the rain and this gives peace of mind and better safety. There is a huge difference in wet performance on car tires. I expect the same on the Spyders, thus the purchase of the Vredesteins. Doesn't hurt that they come very highly recommended on the forum but a large group of satisfied users. Thanks guys!
In closing, a real world example from my past: Ten years ago, I drove a 2wd Ford Ranger to work. It had a set of Goodyear Wrangler tires, which literally wore almost forever (100K miles) but had marginal traction in snow and on wet pavement. I replaced the Wranglers with a set of the original Goodyear TripleTread tires on the Ranger. The TripleTread was a direction tire with a Mountain Snowflake rating. It was somewhat similar to the new Quatracs. The traction on snow or wet pavement was much better than any tire I had EVER driven on any vehicle. They were amazing tires for traction...but they were worn out in 40K miles of of paved driving. I loved the traction but couldn't afford to replace a set of tires every year as I drove over 100 miles per day in my commute.
For the Spyders, the extra safety from the Vredesteins with their great wet road traction is at the top of my list as it does rain here in the midwest too.