rsg

Okay I know this is a wheel question but it is specific to the LS400. Is the ride quality with 20" wheels much worse than 18" and 19"? I want to go with the 20s but first of all the price difference is pretty large compared to slightly smaller wheels. So basically I am looking for an excuse to go with 19s
Especially to those who have 20s with the air suspension, please let me know what you think.

ATSOU

I think 20s will ride better than the 19s. Some people run 245-35 on 20s and 235-35 on 19s........Well about the 18s......Most people run 240-40 on 18s. So I think the ride will be about the same.

SWEETSOUND2001

Generally, the larger you go, the worse your ride quality will get. First of all, you tires will be thinner with stiffer sidewalls transmitting more NVH (noise, vibration, harsness) to the car. The wheels are likely to have much higher unspung weight so the suspension will not be able to control the motion of the wheels as well as the lighter stock wheels. Here's an example:
I have a 93 LS400 and my stock wheels and tires weigh about 40 pounds per corner. I recently mounted 17" 2001 LS430 wheels and tires. Handling was greatly improved, overall ride quality was virtually the same since sidewall is almost the same size but bumps were more pronounced and had more oscillations since the wheels were at least 10 pounds heavier per corner. You will also notice a decrease in acceleration and increase in braking distance since the car has to work harder to control the extra weight.

I think that just about sums it up.

Manaray

On a LS, you should run:

245/40-19 Front
275/35-19 Rear

You can even do those on a GS (one of our members has that setup) and even on a SC. On GS and SC, it's a tad bit taller than the stock wheels (so the speed is off a little) but on a LS, it should be right on...

Also, you'll get a better ride with that setup the either the 19" or 20" setup you listed due to the larger sidewalls...

As for 245/35-19 vs 245/35-20, for me, they ride the same.

LOTC

I have had 15's,18's and I really felt no difference except for needing more power to turn the steering wheels. Im gunna put on some 20's soon to see how those feel like.

I was just riding on my friends truck with 22's with 295-30-22 and it didnt feel as rough as I thought although he ran over a nail the other day and blew his tire on the side apart and it crack his rim on the side that kinda worries me when I get my 20's on.