Heavy inner tire wear

[ATB88]

Took a look at my tires for the first time in a while, and, wow, very heavy wear on the very inside. It's like the last 1/2 inch of width on the inside was scooped out vs the rest of the contact surface. Both front and rear, but more pronounced at rear. Obviously need 4 new tires, but it also seems like something is wrong, suspension wise.

Rear shocks and associated hardware were replaced with new konis 15k-20k miles ago with new rear tires. RTABs replaced 30k miles (2.5 years) ago with OEM Z4M version with plastic limiters. FCABS replaced about 25k miles (2 years) ago with stock. I almost certainly need new front struts, but it seems the problem is front and rear. Could it just be alignment?

Thanks for any suggestions!

[K-Dawg]

If everything is solid with no play, then alignment. Most likely toe.

[Nate047]

Since you're in east LA, bring it to Chewerks, or Evasive is also good. West End and Johnson's Alignment are great but those are on the west side.

[sapote]

Took a look at my tires for the first time in a while, and, wow, very heavy wear on the very inside. It's like the last 1/2 inch of width on the inside was scooped out vs the rest of the contact surface. Both front and rear, but more pronounced at rear.

I'm curious. Can you eye ball from the rear of the car: set the front wheels straight ahead, from the back, looking at mid height through the rear tire and sight through the trailing and leading edge of the tire, and see if the optical line intercept the front tire? Do this on both sides, and the optical lines intercepts at the same part of the front tires? This will tell roughly the rear toe.
Do from front for the front toe too.

[Tbonem3]

If alignment, it'd have to be toe AND camber. Just toe will cause more accelerated wear across the entire tire (more or less).

Are you on reversed stock mounts? Or at least pulled pins?

[mrgizmo04]

What driving conditions does the car see and what camber are you running? Mostly highway/street miles (not canyon/spirited) with a lot of camber will result in overloading the insides. 15-20k miles on rears sounds like plenty. How many miles on fronts? Pics?

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[zivagolee]

I run -3.5 camber in front with 0 toe and my insides corded after 8k miles (ps4s).

[cobra]

My front tires were just like that and I believe it is a combination of camber and toe. My camber was set at 1.5 degrees so I reduced it to 1.0 with no ill effects.

[dl.m3]

I'm curious. Can you eye ball from the rear of the car: set the front wheels straight ahead, from the back, looking at mid height through the rear tire and sight through the trailing and leading edge of the tire, and see if the optical line intercept the front tire? Do this on both sides, and the optical lines intercepts at the same part of the front tires? This will tell roughly the rear toe.
Do from front for the front toe too.

I tried this but it doesnt work that well for these cars since I think our front and rear hubs have different track widths. Plus more complications if running non-stock offsets. Its a good ballpark method nonetheless.

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[Casa de Mesa]

Not sure how you drive, but I agree this sounds like a classic case of too much toe out combined with too much negative camber.

Here is my setup. I have the starting measurements on left, target in middle (what I wanted to get the car as close to as possible) and then actual measured end result on right. I don't have all of the end results plugged in on the pic, but you get the idea. I can upload the full file if you want at some point. The target is what I ended up running this time and so far, I like it a lot. This works well for my car and suspension.

I pulled a bit of negative camber out (more positive) and added toe-in. This is a street car that I will drive "spirited" but it's still a street car. This is WAY more toe-in than others will run, but so far (1,000 miles) I really like the setup for a compromise alignment. That is, it's not a dedicated track car that needs a knife's edge turn in. It still turns in fantastic, but isn't super twitchy. Use my setup as a reference only.

It's too early to tell for sure about wear, but I'm getting extremely even wear and extremely even tire temps across the face of the tire - within 5 degrees F.

[Slideways]

Not sure how you drive, but I agree this sounds like a classic case of too much toe out combined with too much negative camber.

Here is my setup. I have the starting measurements on left, target in middle (what I wanted to get the car as close to as possible) and then actual measured end result on right. I don't have all of the end results plugged in on the pic, but you get the idea. I can upload the full file if you want at some point. The target is what I ended up running this time and so far, I like it a lot. This works well for my car and suspension.

I pulled a bit of negative camber out (more positive) and added toe-in. This is a street car that I will drive "spirited" but it's still a street car. This is WAY more toe-in than others will run, but so far (1,000 miles) I really like the setup for a compromise alignment. That is, it's not a dedicated track car that needs a knife's edge turn in. It still turns in fantastic, but isn't super twitchy. Use my setup as a reference only.

It's too early to tell for sure about wear, but I'm getting extremely even wear and extremely even tire temps across the face of the tire - within 5 degrees F.

Nice setup! What is good way to check if the ground is level for a string alinement? Is it possible to accurately check toe, within 0.5mm, if it is not perfectly level? I know it needs to be perfectly level to check camber.

[elbert]

Nice setup! What is good way to check if the ground is level for a string alinement? Is it possible to accurately check toe, within 0.5mm, if it is not perfectly level? I know it needs to be perfectly level to check camber.

Get a really long level. You can also use straight piece of metal stock with a small level. Also get some cheap vinyl floor tiles.
Mark on the garage floor where you will be aligning your car. Mark out where the tires contact your garage floor.
Stack the floor tiles so all four spots are level to each other. Bonus points if you grease the tiles so they can slip around without binding.
For future reference, mark the tiles so you know how many go in each stack.

[Casa de Mesa]

Slideways I will reply more later but elbert is spot on. I use a laser level and carpenter's square like in this article. Vinyl floor tiles from Home Depot or wherever are a great way to shim under a given wheel in about 1/8" increments. So long as my delta across 4 tires (the platform they rest on during alignment) is less than 0.125", I call it good enough. IMHO for alignments, it's more important to get side-to-side more accurate than it is front-to-rear, UNLESS you are also corner weighting.

https://www.motortrend.com/how-to/hr...ignment-guide/

"For accurate corner weights, all four scale pads must be on a level plane because variances are read by the scales as a change in corner weight. We made a simple scale-leveling system using an inexpensive laser level and a carpenter's universal square. The laser beam is focused on the universal square, which is set on each scale pad. The square is marked in inch increments, and each pad is shimmed to the same height."

[Casa de Mesa]

It's like the last 1/2 inch of width on the inside was scooped out vs the rest of the contact surface. Both front and rear, but more pronounced at rear.

Do you have a pic of the wear?