Using your article on the 2007 Tundra, other reviews, test drives, etc., I purchased a double cab, short bed SR5 with the 6 cylinder engine. I get good gas mileage and love the excellent build quality of the Toyota. I use the truck for DIY projects and just turned 10K in mileage.
The problem: the ride is choppy and the worst of any of the six pickups I have owned including heavy duty models used to haul campers. I have contacted my dealer service manager, Toyota Zone and the Company, and have not received any help in trying to obtain a more civilized ride.
Tundra's stiff ride is a historic characteristic of Toyota built pickups and SUVs, as compared to American made trucks. The common consensus is Toyota trucks are geared more toward work and hauling, than everyday driving.
Like all pickups, the bed is designed to haul cargo. So the suspension is engineered to ride at its best with weight applied. Put a 500 pound load in the back of your Tundra and check out the improved ride quality.
As far as softening the ride of an unladen pickup is concerned, it boils down to tires, shocks and springs. But aftermarket truck suspension part's manufacturers focus their products on the more abundant performance and off-road buyers.
I suggest taking it one step at a time. Hard to believe, but some folks are still unaware of correct tire pressure specifications, and pump their tires up to the max PSI molded into the sidewall. Look up the specs up in your owner's manual, or read the sticker inside the driver's side door-jam. Then apply the correct pressures all-the-way-around. In your case, maybe a couple of PSI on the low side.
If that doesn't help, you can try a set of tires with less aggressive tread patterns comprised of softer rubber compounds. When you look up the recommended tires for your truck with tire company software, you'll have a few choices to work with. But the latest generation Tundra is a tough truck, so don't go outside of the designs they suggest.
It may still be what you consider a hard ride after fine tuning the tires, but after that it can get expensive, and still might not produce the results you're looking for. You can check with the bigger shock and spring companies and see what they suggest to cushion the ride, but again, most truck products focus on performance handling and climbing mountains. That can mean higher spring rates and more restrictive shock damping.