I have a 96 850 turbo wagon. Since I just bought some new tires, I thought I'd pass along my findings regarding speed ratings.

Volvo says you have to have H rated or better. I bought the car used with Michelin Hydroedge (in Dec. '06), 205/55R16, T rated. I had no issues running the lower speed rating, never spun a tire off the wheels, never had an issue cornering at highspeed, never a problem cruising the highwy at 75.

I think the problem comes in when you are WOT. But since no one in the US drives the Autobahn regularly, the speed rating usually is not an issue.
I guess if you live in Arizona desert and regularly wind up to 139+, then it would be.

BTW, the Hydroedge do not perform any better in wet conditions than an all season tire. I was not impressed, and at $165, you'd better be saying "WOW!" when it rains...
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'96 855 Wagon, 200k (and formerly 97 850, 120k)

While V ratings are normally not needed in the USA or Canada, there is a stiffer sidewall construction in the higher speed tires.

T suits me just fine, not being overly aggressive and not liking being stopped by troopers.

Klaus
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Common sense trumps a PhD