I'm not sure about the weight issue but as a rule,the lower the tire profile the firmer the ride. I am assuming the tires are 50 profile or less.
Bear in mind these tires were designed for lighter 'nimble' sports cars and as a result have much less sidewall 'flex'.
They are always going to be a compromise between looks and comfort. thumbs_up
It might be worth looking up www.momo.com
to see if your wheels are on their site. It may give you load ratings. Watch though,it'll probably be in metric! dang
As LONGBOX55 said,your overall drivetrain/suspension setup will also have a bearing on the ride quality.
Hope this helps
Jock wave

1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.