So recently I put on 19x8.5 and 9.5 38et wheels on 235/35/19 and 265/30/19 tires, on my MY16 3IS 300.

I did many months of searching and found someone had the exact setup and was told there was no issues at all.

My car is AWD and I do not intend to ever lower it.

So after installation, driving the car back to home to drop off the 4 sets of Winter tires/OEM wheels. I heard a slight rub sound in the rear when exiting a turn onto a hill (the sound was very small). Also heard another one when I hit a pretty good size bump.

After dropping the tires/wheels off, I return to work and did not hear any more rubbing sound. Either there was no bump or it means I only rub during heavy load.

Question is, if I get occasional rubbing in the rear (obviously) due to full load 200+ lb and full tank of gas too, should I be concerned? or if this is something I can manage without worrying too much?

the opinion and advice seems to sway to the extreme on both side, some say any rub is just bad and is very dangerous, but some say it depends on where it is rubbing. Some say it can damage your sidewall on your tire over time and some say it takes quite a lot to chew thru your tires.

I was hoping someone may know what action I should take

Gen

 

First off, seems surprising that you are rubbing in the rear at stock height. Plenty of folks run 19X9.5 +38 to +42 on the rear, with lowered suspension, and don't have rubbing.
Of course, as you point out, it only happened with the weight of the other wheels in the vehicle.

A set of F Sport wheels would be about 110lbs total, and then add a tank of gas to that. So pretty much the weight of an adult.

Any rubbing is bad when the vehicle is driving as the damage to the tire can be unpredictable depending on speed, force of contact, etc.
And if it's rubbing on painted metal, then that introduces the potential of rust forming on the vehicle as the paint gets rubbed through.

You could manage load in the vehicle so that it doesn't rub, or swap out the rears for a 255/30/19.
If you can confirm where it's rubbing first, that could present other possible solutions.

 

just put masking tape around the fenders to locate the rub? that is what I saw a while ago

 

even though you may be using the same tire and wheel size/offset as others who don't rub, not all tires run the same widths. Some have blockier shoulders, some are a good amount wider. Then, you also have to take into account the cars that are lowered may actually have more room because of the natural tendency for the wheels to gain negative camber.

As far as this being bad or dangerous, it all depends on how much its rubbing. If there's a sharp edge rubbing against the tire and tearing through the sidewall then it should probably be remedied sooner than later. If it's just a minor rub that isn't even cutting into the side wall visibly, then you can probably bide your time and run it longer, but just keep an eye on it.

 

I am going to try and monitor and understand just how much it is rubbing if when it does. as someone mention, and I agree, I read many running the same setup without any issues. Then again, maybe everyone was only commenting on solo under ideal condition.

once I determine where and how much it is rubbing, I have to look at some options. Anyone can comment using camber adjustment over rolling fenders being a solution? or is this myth and trade off would not be good

 

Putting masking tape on the fenders is definitely one way to see where it's rubbing.
The rear fenders on the IS are already factory rolled, there is literally nothing left to roll.
You could stretch the fender slightly, just before the paint cracks, but I wouldn't necessarily recommend this...maybe as a last resort.

SPC makes camber arms for the rear. If you could dial in a little more camber, and stay within factory specs, that will get you a little more clearance, and minimize any camber wear.

 

Also, you can easily run a 255 on a 9.5 and it will be perfectly safe and can look stretched or not stretched depending on the tire model choice. It should help some with clearance.

 

According to my Calculation 235/35/19 is [ 0.0195 inch ] bigger than 225/40/18 and 265/30/19 is [ 0.0116 inch ] bigger than 225/35/18 if you want OEM spec perfect size no rub over a Bump or sharp turn will be 225/35/19 front - 255/30/19 rear.
Because 225/35/19 is [ 0.0057 inch ] bigger and thats fine and 255/30/19 is [ -0.002 inch ] smaller and thats Perfect for oem

I have mentioned this in hundred posts and threads before, people just don't care but the truth is we can't never out smart Engineer, you cannot have bigger alternative wheel/tires over stock OEM size, because it will effect braking system Speed ODO reader and RUB over a bump or sharp turn, if its a bit bigger like this one 0.0057 2 digit is fine but not 0.0111 for example, the rear is perfect because its -0.0002 , if it smaller the number can goes down to -0.0222 for example but if you are not lower stay as close to OEM size as you can.

To be honest i learnt these for many years, tested, done it seen it, had issue with it, seen other Lexus had rubbing issue and came back to our shop as well.

 

well I run all season performance cont for 265/30/19, they dont have 255/30/19, neither do the Mich Pilot sport AS3 plus which was my 2nd choice

 

It's not normal for the wheel to be rubbing. So any rubbing is not ideal.

My advice for a fix is what I (and others now) tell people on the BMW forums: buy the correct size wheels/tires.

 

if tire brand don't have your size, go for another brand, Michellin is not bad, there are many famous brands out there, most of AWD cars are very sensitive , it has to be precised or encounter problem.

most of Toyota/Lexus they rubs at the rear Fender when you hit a bump or carry 5 persons in car. back in the 90s my TRD specs Toyota Solara did slightly rub in the rear TRD lower springs is 1 inch lowered with TRD setup 225/45/17 all around, later on i changed to 2 inches lower with 225/40/18 all around offset also +40, damn bro rubbed like crazy, what i did to fixed ?

FENDER ROLLED ! after rolled the fender and go back to 225/45/17 setup, the rub GONE, i don't think we can fender roll Lexus IS, but you can go bigger OFFSET to reduce the rubbing, your current offset is +38 , you said you put +38 offset all around ? what about keep +38 in the front and +45 in the rear ? and the rear setup will be like mine or issue. well you can go +40 offset rear !

 

anyone here was able to cure their rubbing issue by just camber adjustment?

 

I'm sure if you get the SPC arms for the rear and have the alignment shop adjust the rear camber to the maximum negative, WITHIN THE FACTORY SPEC RANGE, then it should be fine for the rubbing.
Otherwise, change the tire...either way you gotta spend some dollars to fix this.

 

ok so I think I have narrowed down to 3 options to fix this issue.

Feel free to comment if you can help me decide which is the better way.

in short my 19s offset 38+ is rubbing under full load on the rear back side (left), I read everyone who has 40+ offset was fine. No problem at all. hence I am really 2mm from the sweet spot.

I dont want to change tires or wheels as I am pretty set on the brand and based on my own reasons. wheels dont come in narrower 19s nor does the tire have 255/30 (current 265/30)

I am stuck with these options

1. Fender roll - the problem is Lexus unlike other cars, dont have much to work with, as the fender is already quite thin. the risk of damaging or cracking the paint or causing rust down the road is what I have to consider.
2. Chamber adjustment - as someone suggested for me , getting SPC control arm for the rear and changing or adding negative cam to the rear side but depending on how much I need to adjust, risk with this is chewing thru my tires.
3. Modify wheel -I found a local shop that can machine down the center bore/ring and get it down 2mm so that I basically change the offset of the wheel to 40+ and it only cost about 50 per wheel to do this.

Now what does everyone think? option 3 is most cost effective, it will also depend on if the center bore/ring is thick enough for this operation as no wheels are alike. I like option 2 because negative camber is usually a good thing for improving handling anyways and gives me future option for wheel choices. I am less keen on option 1 for the risk of body panel damage where it may be irreversible.

 

1) Fender rolls are destructive, non reversible. Also promotes rust, paint peeling/flaking, and just plain looks bad. Resale value too. Don't!

2) Least evil of the bunch, but unless you do the actual math, you're just playing guessing games. You nailed it (no pun) you risk ruining your tires just so you can get ill-fitting tires/wheels to fit in the first place.

3) Nope. Your life is literally riding on your wheels. As cars are required to be as light and efficient as possible, without computer modeling/simulations, you have no idea what risk you've just created by reducing the mass of your wheels. As it is, they are probably at their limits. Once microcracks form on the back of the wheels, that's not something you'll notice until you're doing 80 down the highway. Not to mention other problems you might create with vibration, corrosion, etc. you're basically experimenting with your life there. Is it worth it?

Just showing the general nature of wheels cracking due to fatigue. Shaving a wheel down even more would scare me.