3IS vs 4IS

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Aug 31, 2022 | 09:33 AM

#16

arentz07

Moderator

Joined: Nov 2016

Posts: 9,593

Likes: 4,784

From: GA

Quote:

Originally Posted by E46CT

Someone can chime in with specifics but pretty sure 85% (if not 99%) of that ride quality you're experiencing vs. your old 2016 came from the 1st refresh in 2017 when the 2017 got essentially GS front suspension dual balljoint/virtual axis setup. a parts bin upgrade/QOL improvement (been a while since I thought about it but that's what i remember)

Then for 2021+ i think it was largely bushing tuning.

Also, it may be worth mentioning, but the tire diameter has been increased on all ISes, from roughly 25 inches to 26.4 inches. Even though the aspect ratio of the tire is the same front and rear, there is a little more tire sidewall than before. I suspect this plays a role as well.

Prior base tire:
Front/Rear: 225/45R17

Prior optional tire package:
Front: 225/40R18
Rear: 255/35R18

New base tire:
Front/Rear: 235/45R18

New optional tire package:
Front/Rear: 235/40R19

New F Sport tire package:
Front: 235/40R19
Rear: 265/35R19

Lexus claims suspension changes were made for MY2021, though, to which prior year it's relative (assuming 2020 would be natural) is not stated.

Quote:

Complementing the enhancements to overall rigidity, multiple refinements were made to the suspension setup. For starters, engineers targeted a reduction in unsprung weight. The new IS features coil springs that are 20 percent lighter than the outgoing model. New A-arms are employed as well that feature a forged aluminum material versus the outgoing steel composition, resulting in an 18 percent weight reduction. Engineers also opted for a new material for the suspension stabilizer bar to optimize the diameter and thickness to provide a 17 percent weight reduction.

Also, I think non-AVS cars get swing-valve dampers as well, which are supposed to do a better job at filtering smallish impacts from the road.

Last edited by arentz07; Aug 31, 2022 at 10:41 AM.

Aug 31, 2022 | 10:14 AM

#17

RA050224

Driver

Joined: May 2022

Posts: 60

Likes: 15

From: VA

The 2022s are 235/40R19 all around on the AWD models like mine (300).

Aug 31, 2022 | 10:46 AM

#18

arentz07

Moderator

Joined: Nov 2016

Posts: 9,593

Likes: 4,784

From: GA

Quote:

Originally Posted by atomicva

The 2022s are 235/40R19 all around on the AWD models like mine (300).

If you have the optional 19-inch wheels on an IS 300, this is correct. IS 350 always has the staggered fitment with 265-width rear tires. I updated the above post.