I was doing some research on the tires that are on my new to me 06. They are the 245/45/R18 size. They are the larger size of the 2. How did Lexus decide which model's get a certain size???

The car has Hankook Ventus V4ES on it. They are pretty loud in my opinion, can't wait till they are worn out!

 

Firm ride/ handling package, or whatever they called it follows the trend of bigger wheels and less rubber btwn. the rim and the road. I personally like my LS's 16" wheels and tires. They give a fantastic, smooth ride and handling is still good if you pick the right tire; plus the 16" tires are a lot cheaper than 17s or 18s.
Even my Mazda Miata came with 17s. I switched to 15s.

 

True, but I'm wondering how or why some models take 17's and 18's. Usually it is because the car has a certain package??

 

I believe for '04 on the 17" were across the board with 18" for Sport or standalone option

 

Huge space-age Japanese supercomputers with highly advanced CADs. That's how

 

That is correct. The sport package was available only on the Premium and Modern Luxury trim levels. Otherwise, 18" wheels were available as a standalone option. Both sizes were also available in optional chrome finish.

 

My 18's are sort of a chrome/smoke color.

 

Love the 18" look, had 17" ony LS when I first got it and it was fine, bit mow running on 16" and very plush.

 

There is an aftermarket copy of the 5-spoke factory 18" wheel that is finished in black chrome, which would appear as you describe. A search will turn up some pics.

 

They are definitely factory wheels.

 

I'll still bet the older 16s are smoother and quieter. After, that is one of the LS430's main attributes, a smooth, quiet, comfortable ride.