I have 2011 LS460 regular suspension. Ride is smooth on little bumpy road. but when going over very bumpy rode or pothole, the car feels almost no suspension(feels like nothing between body and tire). On the same very bumpy road, my 06 LS430 is more forgiving.

If the surface quickly going down and up(like a little V shape) when driving 60km per hour, the car feels almost hit the buttom.

I still have the extended warranty and have lexus tech checked and they couldn't find any problem. Somehow I find LS430 is more forgiving than LS460 on very road. Do you guys have the same issue?

 

What size wheels are on your LS460 and what size wheels are on your LS430?

Both the same suspension? (I.e both air or both coil)?

 

I checked. Kumo tire on LS460 is 235/50R18, that is the default size labeled on the car. Tire on LS430 is 17 inch while the label printed 18 inch .

 

When you say the label is printed 18 inch, how is the wheel 17 inch? Can you post the tire size for your 430?

What PSI are you running in the tires on the 460? Try reducing it to 30.

 

LS460 is running PSI 33 as recommended by Lexus. Is it really because of the tire or suspension? My tire on LS430 is R17

 

most of the road is smooth ride with LS460, but I really need to watch the V shape surface and pothole now for my LS460. It will either give me "thump" sound for V shape surface or feel no suspension on pothole. While I never need to worry about them with my LS430

 

The issue is probably the 17 inch wheels on the 430 vs the 18s on the 460, but the tire pressure is playing a role too. Try reducing the cold pressure to 30. Tire pressures are higher now than they used to be to produce better fuel economy figures. My 460 rides considerably better at a PSI of 30 than it does at 33.

Those Kumho tires are also not helping, what sort of tires are on the 430?

 

I have a '12 with Kumho's as well - not my choice, selling dealer installed new tires (which were also dirt cheap lol, i think under 600 for the set which is unfitting for such a luxury car). To be honest, I find the ride to be a bit sportier than the 430 but feel at the same times the bumps are better dampened, even with cheap tires. I can really tell the suspension system was very well engineered despite having so-so tires on. Big bumps are not pleasant I will have to agree, but then I'm not sure they're particularly nice in any car save for maybe a Phantom. I don't have the 430 anymore so I don't have it to readily compare with. I will say that it rides noticeably more quiet than my mom's 5 series (fantastic car, not knocking it in any way, handles like a go-cart) which rides on some Michelin Premier A/S's.

I would say look into replacing the tires. I know in a about a yr or so when I land my first official practicing job after residency, I am going to treat myself to a brand new set of tires. I was thinking either Michelin Primacy (had the MXV4 on my 430 loved them best tires I've ever had), or the Pirelli P7s as I've heard good things about those. Sadly the Michelin Premiers which is probably the best all around tire isn't available in our wheel sizes other than the light truck tires which I hear don't ride as well due to stiffer sidewalls.

 

My 430 use primacy tire. My new Kumho tire on 460 is put on by the cheap dealer too.

 

My 06 430 right rear has occasionly some "ku-long" sound when it is on bumpy road last week. The dealer said it need to replace the shock absorber. Mine is not air suspension, hope it doesn't cost me too much while my warranty is just expired.

 

So you have a 430 on the smoothest quietest tires and the 17s, and the 460 on 18s and crummy tires. That's the issue, I would put a set of better tires on the 460, but immediately I would reduce the PSI to 30 I bet that will make a big difference.

 

Steve, novice question. Isn't 30 psi under inflation when 33-35 psi is recommended? Won't it reduce tire life and gas mileage? I see the benefit of better ride quality, so it is a trade off.

 

Not necessarily. The recommended pressures are set to achieve numerous goals. They're maximizing ride, tire life, fuel economy. In modern times fuel economy has become way more important than it used to be, with increasing CAFE standards, etc. The EPA tests cars based on their factory specs, so tires aired to factory PSI. The higher the pressure, the higher the economy.

If you look at older Lexus vehicles you will find their recommended pressures were a lot lower than they are now. For instance, my 98 LS400 had a recommended factory pressure of 29. My LS430 was I believe 30. My LS460 is 33. My 03 ES300 was 29, my 10 ES350 was 31, new ES350s are 33. These vehicles haven't changed much, they're all about the same weight, etc. Pressures have gone up in an effort to improve fuel economy in an era where that rating is more important to carmakers than the smoothest ride.

I've been running my LS460 at 30-31PSI since it was new, and I haven't seen any premature wear. I replaced the OEM Bridgestones with the Pirellis at 9,000 miles, but those Pirellis now have 14,000 miles on them without any premature or unusual wear. The 2013 GS I had before the LS I also ran at 30-31 PSI to improve ride (33 factory on that too), and I had the original tires for 34,000 miles with no unusual wear, I replaced those because they were uniformly down to ~ 4/32nds in tread depth.

So, I'm pretty confident that we can run these cars at lower pressures, get a better ride and not suffer any premature tire wear. Try the lower pressure, you'll notice the difference. I too felt my 460 was firmer with really heavy bumps until I did that...it still may be a little bit, but I don't have a 430 to compare it to side to side like the OP. Theres another similar discussion going on right now in the ES forum.

 

Due to setup or age of components one LS may be softer than another, but when you say "weak" it suggests a part was damaged or is easily damaged. Dampening is a tricky art, and I'm certain various shock companies broach topic in different ways. Moreover, when I went from 18 to 20 inch tires (40psi) and poly bushings I still think the LS460 suspension is very forgiving considering the hardware. How many miles are on both cars?

 

My 2011 LS460 has 60k miles on it. My 06 LS430 recommended PSI is also 33.

I think most of the LS owner are very picky and attention to detailed like me(that is why they drive LS). I will change my tires to see if it makse a difference even though my Kumho tires are still pretty new. I am living in Canada and have cold and snowy weather. What tires can you guys recommended for my 2011 LS460 AWD?

My LS430 is RWD, so I have to have winter tires. My wife has 2010 RX350 AWD and is OK without winter tire.