Hey I have this question as well...35 truck looking to put 37s on it. From what I have gathered so far, the 37 package does have a stiffer set up, we get more travel out of the suspension with the 35s so putting a 2 inch taller tire can run us into issue when going off road and needing suspension to do what it does, it's traveling more with big tires, this is where I think guys are cutting tires or getting unwanted rubbing which doesn't exist when on street use where the bumps or no where near what it is off road. My question is what to we need to buy for our suspension to get it to the 37 package...a leveling kit or new springs or new coils completely? What about 325/60 so it would be an inch taller going from a 34.4" tire stock to a 35.4" tire, this could probably be done without any modification to the stock 35 suspension. I've ordered 37s but in the process of cancelling because now I am uneasy on the suspension travel with bigger tires, fitment and bolt will be completely fine, it is the travel that becomes the bigger issue....Then there is also fuel economy, power loss, and speedometer issues with the 37 inch tire to consider.