Not sure if I'm being much help, but thought I'd chime in on the matter.
If you look at my sig, I've got 20x9.5 rims with 35x12.50 Toyo M/T. Maybe it will help your decision while you wait for someone with 18" wheels to chime in:cheers:
-edit-
The road noise is there, but it's not as bad as other M/T. Unfortunately, all M/T tires are going to make quite a bit of noise, but in my experience the Toyo's are the quietest! Tread life is something that I can't help with as I just put mine on a week ago.
If you look at my sig, I've got 20x9.5 rims with 35x12.50 Toyo M/T. Maybe it will help your decision while you wait for someone with 18" wheels to chime in:cheers:
-edit-
The road noise is there, but it's not as bad as other M/T. Unfortunately, all M/T tires are going to make quite a bit of noise, but in my experience the Toyo's are the quietest! Tread life is something that I can't help with as I just put mine on a week ago.