I just wanted to share my experience regarding the 18" wheels. I saw my 06 LS 430 online, it was super clean, had the timing belt done, 4 new tires and new brakes all around. It was silver which I didn't like but it was so clean that it was obvious it was well cared for. I drove to the dealer 1 hour away and went into the test drive figuring I was not going to buy it because it had 18" wheels and tires. I expected the ride to be very harsh and a soft ride is my #1 priority,which was why I was looking to sell my 06 Avalon, it had 17" wheels and rode too hard for my taste. To my surprise the LS with 18's rode quite smoothly, so much so that I bought the car. The tires even had 40 psi inflation. This was a bonus for me because I knew it would ride even smoother with 30 psi. and I still have the option of going down to 16" wheels in the future for the ultimate smooth ride if I want to. I'm pretty picky about a smooth ride too but honestly it's still buttery smooth on all but the harshest bumps or recessed manhole covers.It rides sooo much better than the Avalon. So far I have kept the pressures up to increase tire life and slightly improve turn in response and better fuel economy. I did this with my 1992 LS 400. They ride so smoothly they can tolerate higher tire pressures without being too harsh. On the Avalon I had to decrease the tire pressures to 27 psi and it still rode too stiff for me. The point I was trying to make with this long-winded thread is that the brand of tire probably makes a big difference in ride quality as well as the wheel diameter. The tires on my LS are Goodyear Assurance Comfortred Touring. My feeling is that the extra cushioning of these tires is compensating for the 18" wheel diameter and low profile tires. I wonder what the ride would be like with 16" wheels and these Comfortred tires. I may find out in a couple of years when these tires wear out. On a side note the 18" 5 spoke wheels look great, I may end up keeping them indefinately.

 

The sticker on your door jam should say 33PSI that is what I would run. The car will feel like butter the tires you have are GY best riding tires for your car according to the GY store.