Interesting that the Gen 6 with same tires recommended 33 psi cold. Increase to 35 psi an economy measure on the Gen 7s? Don’t forget that every 10 deg. F increase results in a tire pressure increase of 1 psi; I run mine at 36 cold (summer) and a highway run will quickly see 40 psi at the tires.

 

After I got delivery of all new 2015 4GS, I thought it handled almost like a compact sedan, however the ride was firm, tied down and tiring!

Initially, I Minus 1 from OEM 19" to 18" of the mid-level trim - however, I still found my brand new 2015 rode much more firmly than my friend's 2014 model year.
Hence, the Lexus parts department compared the suspension part numbers, and lo and behold, we discovered Lexus had changed the coil springs and shock absorbers almost every model year, without any official press release!





Back in 2009, grandson Akio Toyoda took over the reins of TMC.
Akio is an avid racer at the Nurburgring.
Akio stipulated "no more boring cars".
However, Akio is contradictory, because by axing the premium RWD-based GS, LS and not major redesigning IS - Akio now has a range of very boring FWD-based vehicles!

Anyhow, back in 2012, Akio released sporty firmly suspended GS range.
By 2015, the 4GS reached its firmest coil spring calibration!
In 2016, Akio did an about-face, and put back sound insulation, as well as softened the coils and shock absorbers.
Below is a photo of 2015 versus 2016 front coil springs.
Notice how the new softer set of front coil springs has taller unsprung axial height to maintain the same ride height?
If the new softer coil springs have the same unsprung axial height, then the vehicle would have a lower ride height and less suspension travel!
However, I find that the new softer 2016-20 springs and shock absorbers are still not soft riding as my 2005-12 3GS.
The 2016-20 4.5GS midlife refreshed ride is still quite firm, but a little softer and more tolerable than my 2015 model year.

Then I noticed in a thread that it was possible to further downsize to 17" without interfering with the 4GS brake rotors and callipers.
Hence, I Minus 2 to 17" and finally, now I have a "decent" ride - though not a magnificent ride, but a reasonable and tolerable ride.
Thus, I am using tall sidewalls to make up for firmish coil springs and firmish dampers of the 2016-20 4.5GS midlife refresh.

 

Buy a Milton 921 pencil tire pressure gauge on Amazon for about $10.

 

Lowering tire pressures will only do so much before fuel economy, steering, and tire wear are affected.
Lowering tire pressures plays a small role and is simple and cost free.

Downsizing the rims to 18" or even 17" will do more.
However, this is a costlier exercise.

The spring, shock absorbers and roll bar rates will play the biggest role!
However, this is most expensive to modify.

If I'm not wrong, the original version/s of the 7ES released mid-2018 have softer suspension calibration than the 7ES on sale in recent years?
The dealer gives me 7ES loaners every year, so that's how I suspect.

You have to make sure cold tire pressures are the same, and then test drive two model years back to back, and then go on websites like lexuspartsnow.com to determine if the model years are using the same or different part numbers for springs, shock absorbers and roll bars.
The different suspension part numbers do NOT indicate softer or firmer nor by how much, though I wish the factory did specify; only test drive will determine - sometimes, we can't tell the difference despite the difference in part numbers.

 

That's quite an investigation!


Back to tires: due to the temperature and the car tpms complaining, I went from 28-30 to 38-40 psi on my 205/65R16.
I feel more sharp high frequency harshness. And the car is also more "bouncy" on low frequency bumps.

Maybe I should go back to lower pressure to confirm the difference as I usually increase the pressure very fast but let it decrease naturally over many month, so I don't perceive the improvement since its so gradual.

 

The factory recommended tire pressures on door stickers are cold pressures.
However, this does equate to lower early morning temperatures in winter versus higher early morning temperatures in summer.

Once driving and warmed up, the tires will have elevated pressures, and these elevated pressures are normal and should be ignored.
IMO, I wouldn't use lower pressures than you have already used.

 

You can modify the TPMS trip point if you want as specified on page 321 of the owner's manual but 28-30 PSI sounds low. The manual shows 35 PSI for 18" and 19" tires and 36 PSI for 17" tires. I remember my '99 Avalon with 15" tires specified 32 PSI.

I'll bet the 16" soaks up bumps really well.
What specific wheels did you install? Were they from Tire Rack?

 

7ES OEM is 235/40 R19, which is equivalent to 235/45 R18, which is equivalent to 235/50 R17, which is equivalent to 235/55 R16 - which in turn is equivalent to 225/60 R16, which is in turn equivalent to 215/65 R16, or 205/70 R16.

However, he's only using 205/65 R16 - hence he's running a slight smaller rolling circumference with slightly shorter sidewalls, hence he's not really benefiting compared to 205/70 R16.
Hence, he hasn't really taken advantage of the 16" wheel size.
In practice, these days it can be difficult to find series 70 tires.

 

205/70/16 sidewall height = 5.6" tire diameter is 0.8" taller than OEM
205/65/16 sidewall height = 5.2" tire diameter is 0.2" taller than OEM @Lexuspicious
215/55/17 sidewall height = 4.7" OEM 17" tire
235/45/18 sidewall height = 4.2" OEM 18" tire
235/40/19 sidewall height = 3.7" OEM 19" tire

I think we can agree he has markedly increased sidewall height relative to OEM and will benefit with improved ride quality so I'm trying to understand why you say:
"However, he's only using 205/65 R16 - hence he's running a slight smaller rolling circumference with slightly shorter sidewalls, hence he's not really benefiting compared to 205/70 R16"

The 65's have 0.4" less sidewall than 205/70/16 but 205/65/16 will definitely fit. I agree 205/70/16 is preferable but not worth the risk.

We don't know if 205/70/16 will fit since we are now increasing tire height by 0.8" and he did in fact gain 0.5" sidewall height relative to the OEM 17" configuration.
I think he made the best choice considering tire fitment. Not to mention, like you said, 70's have fewer choices.

I applaud your work with springs tires and shocks. One of my big complaints with this car is the ride on rough roads (which we have many around here). It's a bit disappointing to me that Lexus has strayed on this quality.

 

You're right.
The mathematics is complex.
So even though it sounds like 235/40 R19 ≡ [is equivalent to] ≡ 235/45 R18 ≡ 235/50 R17 ≡ 225/55 R17 ≡ 225/60 R16 ≡ 215/65 R16 ≡ 205/70 R16 - this final 205/70 R16 size actually exceeds the 3% rule, hence is illegal!

He has used 205/65 R16 for 5.25" sidewall height which is great.
However, he can still do better by using 215/65 R16 for 5.5" sidewall height - though 205/65 R16 will allow him to do better in the rain and snow.

235-40R19 vs 235-45R18 vs 235-50R17 vs 225-55R17 - Tire and Wheel Plus Sizing | Tire Size Calculator

Am I right when I remember that the original 7ES released in mid-2018 is softer riding than the 7ES updated recent model years?

 

This model:
https://www.tirerack.com/wheels/Whee...S&selectedRear

I just used their wheel finder tool and picked one that was cheap, available, light and not crazy looking.

Your equivalences are flawed.


You just need the tire outer circumference, so you first need the tire outer diameter, which is just 2 sidewall height + the wheel diameter.
For example tire sidewall height = 205 mm * 65%
Outer tire diameter = 2 * 205 mm * 65% + 16 in.
Tire outer circumference = pi * diameter = pi * (2 * 205 mm * 65% + 16 in)

That's math taught at 12 years old. Once you are familiar with what the tire labeling means, it's easy.

I went with this size because it's the one used on the Camry and the one that Tirerack was guaranteeing the fit.
But yes next time I will go to 215/65R16: there's a broader selection of tires available and that's a little bit more sidewall.

 

Unless I'm missing something the 205/65/16 actually have a wider selection vs 215/65/16 at Tire Rack unless you are counting snow tires.

205/65/16 55 total tires 14 snow tires
215/65/16 48 total tires 19 snow tires
215/55/17 121 total tires 17 snow tires

Are you in the least bit concerned the 215/65/16 might be a tad too tall at 0.7" bigger diameter than OEM? I suppose Tire Rack is just being conservative not listing them as guaranteed to fit.

You gain 0.3" more side wall with 215/65/16 compared with 205/65/16 which is nice.

 

Equivalence works well from the starting point at 235/40 R19 all the way down to the limit at 215/65 R16 - but 205/70 R16 was just too far, hence it exceeded the 3% rule.

 

I suspect Tire Rack did not list the 215/65 R16 because the speed variance is 2.23%, whereas the 205/65 R16's speed variance is only a minimal 0.34%.
Though the legal limit is 3%.

https://www.1010tires.com/Tools/Tire...ismetric=False


This chart below is actually more correct, because his OEM was 235/45 R18, and not 235/40 R19.
Because the OEM 235/45 R18 is a slightly smaller rolling diameter/circumference with a shorter sidewall, the smaller wheels with taller sidewall sizes have even slightly bigger overall diameters with slightly taller sidewalls, hence they have even more speed variance at 0.63%, 2.57% and 3.69% respectively.

235-45R18 vs 205-65R16 vs 215-65R16 vs 205-70R16 - Tire and Wheel Plus Sizing | Tire Size Calculator

 

I find myself fine-tuning tire pressure often on my ‘24 ESh, especially at change of seasons. Read your owners manual; there is a procedure for resetting your dashboard numbers.