Sasnuke

While it's possible for the vibration to come from everywhere, the likelihood is that it's coming from one axle...front or rear.
If you're feeling it throughout the vehicle, then there's a good chance it was a wheel(s) on the rear.

I would have suggested the same thing to narrow it down to which wheel(s) it was.

On a side note...the owners manual and repair manual for a 2018 IS both state the wheel nut torque to be 76 ft-lbs. I'm not sure where Discount Tire is getting there information from.
Also, Lexus' only spec for wheel balance is that the Maximum Imbalance is to be no more than 8.0g (0.0176lbs). With everyone saying it's "within spec"...I question what the spec is and where they are getting it from.
The RFB machine will provide the balance as a number that is green (in spec) or red (out of spec), similar to an alignment machine. Being able to see that actual printout from the RFB machine would be a little reassuring of what is "within spec".
Unlike an alignment machine where the alignment specs are set by the manufacturer (Toyota/Lexus), the RFB specs are likely being set by the RFB manufacturer as the machine has no idea what rim from what car is on it.

nitroracer

Discount Tire says they get updates from the factory. Who knows. I stuck with the manual. Maybe someone can check their 2021 manual and report back.

There's a thread on here that talks about RFB and 10# or less being considered within spec for Lexus. I know for Audi it's only 15#, eg.

As far as what's within spec or not, I provided the Road Force Variations above. 14#, 10#, 10# and 5#. The only tire I would be suspect of is the one coming out at 14#, though I'm not sure it would cause vibrations this bad all around the vehicle. I really just think these crappy wheels I bought from Tire Rack aren't mounting properly or are passing their tests but that their machines aren't telling the whole picture.

Hunter balancers aren't gospel and the information they provide are very limited in scope as to what they can actually predict about ride quality, in my experience. It's only a proxy for real-world results. And not a very good one.

Sasnuke

Discount Tire says they get updates from the factory. I'm going to go with no on this one.

Maybe someone can check their 2021 manual and report back. 2021 moved from nuts to bolts, and the spec is 103 ft-lbs. Even if they stuck with nuts and changed the spec to 80, it's not retroactive for all IS models.

Generally for passenger cars anything under 20 pounds(#) would be considered good as no vibration should be felt...however as you have discovered, the real world drive will tell you for sure, and something different.
It's possible the 14 pound wheel could be causing the issue...and I doubt very much the 5 pound wheel is a factor here.

It sounds like you just got a set of crappy rims and/or tires...I guess the question is how will Tire Rack resolve it.

nitroracer

I agree Discount Tire is prob full of it. Either way, that's what they stated right on the receipt. I deferred to the manual.

Yes, generally speaking, 20#'s is fine for maybe a Ford Taurus with tires that have an average or above-average aspect ratio. On a Lexus sports sedan with lower profile tires, not so much.

Right now, Tire Rack is basically telling me to pound sand.

Actually, if we're being specific, some of the email responses have included:

1) "The winter tires have a more aggressive tread pattern than you're used to"
2) "The F-Sport is a sports car with sophisticated suspension"
3) "The compound is harder (cringe)"

nitroracer

So just to double check, nobody has had issues with aftermarket wheels on the 3IS assuming proper hub centric rings?

kj07xk

No, but I’ve only tried the one set that is my winter wheel/tire combo. Don’t recall what the wheel brand/model is, tires are Michelin X-ice.
Normally run 80-85 mph on the clean tollways.
As I said earlier, quieter than my summer OEM wheels and Michelin A/S tires. Although the winters are downsized to 17”, so that is probably a contributing factor.

nitroracer

Well, it's been a total dud for me.

Tire Rack is choosing to believe that there's an issue with my vehicle, and not what they sold me, despite the obvious fact that my OEM setup performs beautifully with no issue. $1750 down the drain, will never go back. In the future, any time I mail order tires, I'll be making sure they balance to dang near zero before I even take the stickers off, otherwise they'll be going back.

And of course, I fully expect uneven treadwear on these winters should I continue to drive on them, which means then Michelin will screw me when I go to make a warranty claim. The default will of course be, "it's your car/wheels, not the tires".

Caveat Emptor, as they say.

Napalvr

I had a similar problem with my wife’s Ford Edge. I bought a 20” wheel/tire combo from Tire Rack a few years ago and had nothing but trouble keeping them balanced. I even watched the guy balance them to near perfect and a few hundred miles later it was out again. They even checked the rims with no tires on them for runout. Turned out the tires(Goodyear) were to blame. They were separating beneath the tread. Tire Rack gave me $500 towards a new set(any manufacturer of my choice). I’ve got nothing but good things to say about them. Sorry to hear of your bad experience

nitroracer

Who and how was it determined the issue was with Goodyear? After how many miles of driving? There's usually a manufacturer guarantee you can rely on first, and if it was a warranty issue, that would be very odd for TireRack to give you actual cash when the manufacturer would just take them back.

Sasnuke

The only other suggestion I can think of is finding a place that does on car balancing.

Here's the conundrum...for all the balancing and RF balancing, the one thing that isn't taken into consideration is the wheel stud holes.
All the balance machines interface with the rim at the hub bore. The hub bore could be perfectly round and perfectly centered in the rim, but that has no bearing on the stud holes, which is where the rim is clamped to the vehicle.
Sure the hub does center the wheel, but the nuts can pull the wheel in any direction as you tighten them down...and I'm talking about a small amount of pull that you may not necessarily see with the naked eye.
Possibly this is where an on car balancing may detect/correct the issue.
At the end of the day it seems like a lot of work for a set of winter wheels.

Consider this anecdotally...my winter wheels are from a 2IS (17 inch rim), all the wheels are bent, although very slightly, and they were corroded AF.
I bought them from a buddy that gave them to me dirt cheap because they were bent...he even spun a couple on the balance machine so I could see it, and sure enough, they are bent.
I sent them out to get cleaned up and powder coated, just to keep the corrosion under control. The guy that powder coated them also installed the winter rims on them when he was done...he said they were all bent.
I installed a set of no name winter tires, Zeta, and they were RF balanced.
You can drive the car at highway speed and you would literally never know the wheels are all bent...no joke.
Of course, I'm not worried about the hub and stud holes being an issue as they are OEM wheels...and even with the no name tires, the RF balance sorted out any vibrations, on wheels that have been confirmed bent by myself and two other people.
Makes you wonder what is wrong with these brand new Motegi wheels.

jcruik

Have you tried mounting the wheels without the hub centric rings? I think most aftermarket wheels require lugs with a conical base, which should be self centering. My Challenger is hub centric, but I don't use any rings with the conical seat Weld Wheels, and it's been a smooth ride at well over 100 mph.

jcruik

Made in China, hit or miss on the quality.

nitroracer

Hmm. I'll have to try that.

It's definitely the wheels, though. It's pretty clear to me that they are not centering properly. I'm just not sure how to go about proving/demonstrating that.

Napalvr

There were at least 20-25K on them. They didn’t actually give me cash I just put it towards another set. They(Tire Rack) called a Goodyear rep and he ok’d it

jcruik

I'm not sure if the IS 350 uses conical lug nuts, but make sure you are installing your wheels with one of the standard 60 degree conical nuts. If you first tighten them slowly by hand in a typical criss-cross sequence before torquing them down, they will self-align the wheel.