What causes rear tire cupping? Nitto g2 555s

[markayash]

If you don't fix the alignment it will happen again..Can rotate them often and help.

Sponsored

 

[loucas-2021]

CoPilot says: Cupping on rear tires is typically caused by a combination of worn suspension components, unbalanced tires, and poor wheel alignment. To address this issue, I recommend consulting a professional for a thorough inspection. Based on the severity, they can advise you on tire replacement or repair options1. If you suspect cupping, try the “coin test”: insert a coin (like a penny) into several tread grooves across the tire. If some areas are noticeably shallower than others, it might be cupping1. Keep those rear tires in top shape!

 

[falcongtho3]

If you're running a square tire set, make sure to rotate them regularly. If it's a staggered set up and the tires are non-directional you can rotate them from side to side to help with the feather wear that occurs naturally.

 

[Snakebyte]

Considering the inside only is wearing I'm sure it is not an air pressure issue. That said, could a slight increase in air pressure have worn the center a bit more than the inside edge?

I'm concerned about wearing the edges (one side or both) prematurely, as I have a tire roar on my new tires at speeds less than 50mph. It is as if the rotational mass at about 50 changes the contact patch pressure from the edges and equalizing contact pressure across the tire width.

The roar occurs with my recently installed 19x11 wheels with Nitto G2 555s tires like you have @Metz3020827.

My door tire label states 32 PSI for stock tires, and it recommends a higher PSI when running high speeds. But of course I am no longer stock on diameter, width, or tire rating.

I don't run track days, run spirited, and I pretty much stay within legal highway speeds. So my question to those on this forum is, what is the optimum PSI for this combination, given that alignment is correct?

Thanks for any insight, experience with those who have gotten good, even wear patterns.

 

[markayash]

Go do a few burnouts and " true" them up

 

[ShadesOfBloo]

They’re nitto g2 555s 305/35r19 on a 19x11 wheel. They’re directional so they’ve never been rotated and they’re down to the wear bars now after 16 months.

I have -2.7° of camber bc I don’t have camber arms and I’m lowered. Is it bc lack of rotation and my alignment ? Do I need to worry it might be something else?

That's a lot of dang camber for street driving. You're lucky your tires lasted this long.

I think 1.5 degrees is a good target for this car.
I like most cars with zero toe, but I'm not sure about my Mustang. It's my only car that has more camber in the rear than the front, and may turn out to be the car that wants a little toe-in at the rear.

The recommended 32psi tire pressure might be fine, as soon as you un-**** your alignment.

 

[Metz3020827]

If you don't fix the alignment it will happen again..Can rotate them often and help.

I have a staggered setup with directional nittos. They can’t be rotated.

 

[Metz3020827]

You are running a lot of rear camber. I'd drop it to -1.75. I never liked the feel of 2 or more negative rear camber.

I don’t know how to change it and neither does my alignment guy I guess. He said everytime he tries to adjust it it goes back to what it was which is -2 something. I’ve only ran into one shop here in AZ that will align lowered cars. So it’s a pain in the ass.

 

[markayash]

I don’t know how to change it and neither does my alignment guy I guess. He said everytime he tries to adjust it it goes back to what it was which is -2 something. I’ve only ran into one shop here in AZ that will align lowered cars. So it’s a pain in the ass.

I did alignments many years ago and Toe end can also cause that. If I remember it was when they were toed out too far

 

[K4fxd]

I don’t know how to change it and neither does my alignment guy I guess.

He is lazy. It is pretty easy to set the rear camber. There is a bolt on the inside of the camber arm, part of the arm closest to the center of the car. You loosen the bolt grab a 4 or 5 foot pry bar and slide the arm to where you want it then tighten the bolt.

Find a performance shop. I know there are some.

I think factory "green" spec is up to -2.5 or something ridiculous for a street car. Gives a funny feeling when turning. -1.5 to -1.75 is a great area to be for the street. Gives plenty of corner grip and keeps forward grip.

Factory adjustment procedure.

https://www.mustang6g.com/forums/attachments/2016-mustang-rear-camber-adjustment-pdf.98794/

 

[Metz3020827]

He is lazy. It is pretty easy to set the rear camber. There is a bolt on the inside of the camber arm, part of the arm closest to the center of the car. You loosen the bolt grab a 4 or 5 foot pry bar and slide the arm to where you want it then tighten the bolt.

Find a performance shop. I know there are some.

I think factory "green" spec is up to -2.5 or something ridiculous for a street car. Gives a funny feeling when turning. -1.5 to -1.75 is a great area to be for the street. Gives plenty of corner grip and keeps forward grip.

Factory adjustment procedure.

https://www.mustang6g.com/forums/attachments/2016-mustang-rear-camber-adjustment-pdf.98794/

Something I should give a try at home? I’d rather do that than pay for an alignment currently. I don’t think toe is the problem since these tires are pretty much close to being done and they just started cupping. The passenger side camber is worse than the driver side and the passenger side has worse cupping.

 

[Metz3020827]

I did alignments many years ago and Toe end can also cause that. If I remember it was when they were toed out too far

I’m not sure if that’s really the problem though. I think it’s the too much negative camber. The passenger side is a lot worse and the passenger side is also tucked in far more than the driver side. Took both wheels off yesterday. I am probably due for an alignment though.

 

[Metz3020827]

He is lazy. It is pretty easy to set the rear camber. There is a bolt on the inside of the camber arm, part of the arm closest to the center of the car. You loosen the bolt grab a 4 or 5 foot pry bar and slide the arm to where you want it then tighten the bolt.

Find a performance shop. I know there are some.

I think factory "green" spec is up to -2.5 or something ridiculous for a street car. Gives a funny feeling when turning. -1.5 to -1.75 is a great area to be for the street. Gives plenty of corner grip and keeps forward grip.

Factory adjustment procedure.

https://www.mustang6g.com/forums/attachments/2016-mustang-rear-camber-adjustment-pdf.98794/

Does the arm adjust in and outwards? Or does it slide back and forth?

 

[K4fxd]

Something I should give a try at home?

The problem is when you move the camber you also change the toe.

If you want to do the camber it is easy except for the drivers side where the fuel filler tube gets in the way.

Take your pry bar and move the arm outside as far as it will go. Move the top of the tire out. This should end up with -1 degree or so, then take it to a shop and get the toe set. You want .1 degree IN on both sides for a total of .2 degrees IN. This will most likely take care of your cupping problems.

 

[K4fxd]

Does the arm adjust in and outwards?

Look at the PDF I posted. You want to move the purple bolt toward the shock.

Sponsored