Wheel compatibility / Ride question

OK I'm looking at the 2012 TRD sport upgrade for the internals on the truck, but I cannot stand the 18" chrome wheels.

So what would happen to the ride / stability of the truck if I changed to 16" TRD offroad style wheel with probably a A/T type tire? I know it won't make me any better offroad, but I won't be doing that much past dirt trails from time to time. The sport model reflects more of where I drive now anyway.

I know the ride will be different and the 18" tires will be stiffer on the road, looking for opinions and info.

 

Thwack...

Bueler, Bueler, anyone care to comment?

 

OK I'll try a bump for a different time of the day.

is my question clear? I know the rims will fit, issue is what the extra sidewall going to do to the truck? Make the sport drive more like an offroad?