I spoke to Mike at Donahoe today and he was very helpful. The Donahoes have a spring rate that is 25 pounds more per inch than factory. 650 versus 625 for factory. If I lift it 3.5" and then the plow goes on and compresses the Donahoe 1 to 1.5" and then combined with a taller tire, I should be fine. But were talking a lot of $$ to experiment.
If only someone would produce a variable rate spring like they have for the pre-07 models, my '05 setup was perfect.
If I could find out what the spring rate was for an '05 Tundra 4WD TRD that would really help as well.
Timbren springs that go where the bump stops are is also an option If I could get them long enough to compensate for the 3.5" lift.
I have used most of the plows out there and the Snow-Way plow with the Down pressure system is by far the best out there for driveways. It is the only plow I will use as it saves me so much time (25%). They have a mount for the '07 Tundra now and a wireless joystick setup to boot.
I had a accident 2 weeks ago that wasn't my fault that totaled my '05 and broke a vertebrae in my back. As long as I can stand the pain and doc says I can, I want to be plowing again this winter. Let's share information on this and figure out a setup, before winter gets here.
Tom