Running figs poly LCA rear mount 90 durameter but still having some inside shoulder wear. I understand this is because this vehicle tends to toe out when braking. Because of that I assume that when aligning you want to have a bit of toe in.

Has anyone uncovered how much toe in to try to shoot for to not eat through this inside shoulder, and promote the most tire contact while breaking, while not dramatically changing the vehicle's handing characteristics while outside of breaking?

Joe Z posts an alignment spec sheet here with 0.1 degrees toe in, curious if that's been enough.
https://www.clublexus.com/forums/is-...eel-right.html

Lobuxracer notes having a bit of toe in here as well.
https://www.clublexus.com/forums/is-...l#post11668810

Thank you.

 

In general terms, 1/16" toed in is the best setting for optimal tire wear.

 

I second that.

1/16 toe in front
1/8 toe in rear

 

It all depends on what bushings you are running. I run -0.04 degrees toe out with solid bushings and have no issues.

 

Thank you. I might just try to give it a shot myself.

 

I've thought about moving to solid bushings since I got the lca's before the solid ones were released. It's nice to hear that they restrict that much movement.

My DWS's look great overall, but I'm definately wearing a strip on the inner shoulder. If anything I'm thinking about moving the toe slightly in if anything just to move the wear point a bit so not to pinpoint this shoulder.

 

I'm starting to question whether it's really toe out under braking that's causing this inner edge wear. My observations don't support this theory. If that was the issue, wouldn't we see a more camber-like wear pattern across the width of the tread especially since the full width of the contact patch is well loaded under braking? Instead what we're seeing is a 1"wide wear strip at the very edge only. The previous owner had almost a 1/4" toe in at the front and it wore a strip to the cords in my brand new PS4S in 1 year. For the last 4 years I've been running -0.16 degrees toe out on my summer track day tires and zero toe on PS4S over the winters. The PS4S still saw the inner 1" wide strip wear and I had to toss them this spring. And this was only from city driving so no heavy high speed braking and with the RR racing usrs bushings too. Notably the track tires with toe out are not seeing any inner edge wear so far even though they experience a lot more abuse.
I believe our inner edge wear issues are more attributed to tires scrubbing the inner edge during tight low speed turns. With the wheels cranked to full lock or near full lock at low speed, the camber gain due to our 8 degrees of caster is causing the outside tire to roll on its inner edge. I've noted that with toe out I get a lot less (almost none) tire shudder/skipping at low speed tight turns. I suspect that toe in works against "toe out on turns" (aka Ackerman steering) and is exacerbating tire scrubbing while it's on its inner edge, while toe out works with "toe out on turns" reducing scrubbing. Just my theory at this point. Take it for what it's worth but I'll be running toe out year round from now on to see how it goes.

 

That's an interesting take, these tires are getting thin on the shoulder, so I can do a bit experimenting.

 

I agree MMI a very interesting theory, keep us posted. I have a 2021 ES350 but joined the thread to be in the link to read what happens as alignment is one of the areas I am playing with on my 2021 ES350 that has inner rear tread wear on both tires with 23K on them.

 

Keep in mind dynamic alignment on a FWD platform is very different from the RWD found in the IS models. It will definitely be interesting to see MMI's observations over time. I am pretty convinced the fundamental problem with the suspension is the bushings and the range of motion they allow under power on/off, and especially braking, so I am watching with interest. Solid bushings in the front have eliminated the tire wear issues even with -0.04 degrees of toe out on my car. I've also spent considerable time making sure the subframe is square with the chassis and equally split left/right and I'm pretty confident this makes a big difference as well.

 

Thanks for the feed back on FWD vs RWD and will also continue to read with interest

 

I took the isf into get an alignment and the results were a bit surprising to me, and points towards maybe the camber having a bigger contribution than the toe as I originally thought.

Camber left -1.3 right -1.5
Toe left 0.03 right 0.03

With these numbers, I think it's more than likely my inner shoulder wear is due to the camber rather than the toe. Though I'm not sure if there is an effective camber adjustment stock.

 

No. Camber isn't a contributor until you get to -2.5. Your subframe is a little off center though, and it might not be square with the centerline of the chassis or the rear subframe.

 

Well that's interesting, what's causing the inner shoulder to wear so much then? If camber isn't it, 0.03 toe in should in theory reduce the amount of toe out while braking, what else is contributing so heavily?

 

It does, but it's not enough. Typical is +0.04 for inside edge wear reduction, but if the subframe isn't square, the car is crabbing and that's definitely a bigger problem. Every book I've read on race car setup says the first step is ensure the axles are square with the centerline of the chassis. If this isn't true, the rest of what you'll be doing is a bandaid at best.