Tire wear info and winter tire questions

Repost, as my old thread went away...

I finally managed to find a tire tread depth gage, and I checked my tires. I took my best estimate/closest whole number when measuring.

I have about 23,000 miles on my 2001 Toyota Prius' OEM tires, I think that's about 2 years of service (I'd have to double-check my notebook in my car for the exact date). My usual pressure is about 41F/39R.

OEM Bridgestone Potenza RE92 XL
P175/65 R14 84S
original tread depth is supposedly 10/32"
Measuring the 4 main grooves, in x/32":
left outside ---> inside; right inside ---> outside
left front: 7, 8, 8, 7 ; right front: 5, 7, 6, 5
eft rear: 6, 7, 7, 7 ; right rear: 6, 6, 5, 4

My husband has about 24,000 miles on his 2004 Toyota Prius with OEM tires.
That's just shy of 2 years. Usual pressure is around 40F/38R.

OEM Goodyear Integrity
P185/65 R15 86S
original tread depth is supposedly 10/32"
Measuring the 3 main grooves, in x/32":
left outside ---> inside; right inside ---> outside
left front: 6, 8, 7 ; right front: 6, 7, 5
left rear: 5, 7, 6 ; right rear: 5, 6, 5

Unfortunately, neither car has been in for an alignment yet. But the tires do get rotated (or so says my paid work orders) at every oil change (6 months or 7500/5000 miles).

So, I have more tread wear on the edges, and it looks like about 2/32" of
tread wear per year...

Door jamb info for the US Prius, any model year, is 35psi front, 33 psi rear.

Most Prius owners tend to report edge wear on their tires. It's especially bad on the 2001-2003 Prius with the Bridgestone Potenza RE92 XL tires. So, to combat this, and to increase MPG, many owners either religiously keep their pressures at the factory 35F/33R, or go up to anything that's within the max. cold pressure as on the sidewall. The tire recommendations from the Classic owners just got translated over to the 2004-? Prius when it came out...

Max cold pressure for the US OEM Bridgestone Potenza RE92 XL tires on the 2001-2003 Prius is 50psi. Max cold pressure for the US OEM Goodyear Integrity tires on the 2004-? Prius is 44psi.

Just some data points for those out there...

Anyhow, the question I have is: is it time to dump these tires, or should I hold onto them for another season? (I know a number of Prius owners hate the OEM tires...)

I know that I need to invest in some snow tires for this upcoming MA winter. Last winter I kept sliding backwards down my paved but icy driveway with my 2001, and my husband slid into a snowbank or two with his 2004 BC (and the front bumper still keeps popping off of some of its clips).

I was thinking of just going straight to some Nokian WR A.W.P.2 tires (4-season tires with the Severe Service emblem) for full-time use, but...

Should I/can I just put the Nokian WR onto the current aluminum rims for this winter, change back to the OEM tires for the upcoming spring/summer/fall 2006, and then remount the WRs for the following winter and keep them on (dump the OEMs next winter)? Or should I get some steel rims just for this winter for the WRs, and then move them back to the alloys when I dump the OEMs?

Or should I just buy some steel rims and winter tires (Bridgestone Blizzak WS50 or Nokian RSI), and then have to look into buying another 3-season tire (Nokian NRHi or i3, LRR tires) in another year or so? (This seems much more expensive and more hassle than just going for the WRs above, but...)

Just looking for any tire/wheel advice. Thanks in advance!