Rear Tire Wear "Bumps" in the inside

[Jemuel]

Hello

Car: 2003 Eclipse GS
Miles: 94,000

To Summarize:

* Struts have less then 20,ooo miles
* Tires have less than 15000 miles
* I have a camber kit
* Alignment Tests come green.

Problem: Rear tires have "bumps" in the inside
Tires: Nankang NS-II 225/40/R18
PSI: 42 front/back

I purchased the vehicle with 78,000 miles three years ago and the tires were in pretty good condition when I bought it from the dealer. I was given a 30 day warranty so I took it to a mechanic for a complete check up. The mechanic told me that the rear struts were bad so they were replaced by the dealer.

I have the Konig Unknown 18 inch rims and they do add some road noise but after a few months of purchasing the vehicle I was washing my car and noticed that the rear tires had "bumps" in the inside of the tire. Other than the bumps, the rear tires are in pretty much brand new condition, is just the inside "bumps". I took it to a local tire shop and I was told I needed a camber kit and that was going to fix it. I decided to get the camber kit along with 4 brand new tires and got it aligned, by this time the car had around 84,000 miles. Everything went fine but after a few months and less than 5,000 miles the same thing happened to the rear tires. This time I took it to Tire kingdom and Firestone to test the alignment and everything came out green.

I rotated the tires yesterday and even though the car runs straight I know the tires in the rear now are going to get the "bumps" too and now the road noise in the front is pretty loud at 80+. I would like to figure out what could be the problem before I purchase a new set of tires. Has anyone had/has this problem? I searched around and most of the issues are related to the front.

Here's apicture but is hard to see, I had to pass my hand over to feel the bumps.
Left: facing out | Right: facing inside



Thanks for your help.

[Silvertune]

Holy christ, 42 psi? That's your problem. You've blown them up so much that daily driving conditions is stretching the cords or something interior to the tire itself. Just because they're low profile doesn't bode 40 psi on the street, maybe for chasing cones but not otherwise.

Why rear and not front? The rear has very little weight on it and that means the tire that makes up the contact patch with the road is under much more tension making it more susceptible for road damage. With the front the weight presses the tire into the road which actually relieves tension in the contact patch. This is essentially the same concept as overfilling your tires at the track but longevity spun instead of handling issues.

[Got Rice Boy]

42 psi is kind of alot.

This is from the 3G FAQ

What pressure should I keep my tires at?
(08/15/2001)

Mitsubishi recommends running the front tires at 32psi and the rear tires at 29psi for normal driving.
For extended high speed driving they recommend 36psi at the front and 33psi at the rear.

I personally recommend running a few 33-34psi at the front and 30-31psi at the rear; at 32psi the front tires look nearly flat and don't offer the rims much protection against road hazards.

Be sure to maintain a 3psi differential between the front and rear tires. If you don't, the car will feel unstable at highway speeds and will not want to travel in a straight line. This kind of behavior is not desired and can be dangerous. The differential is needed due to the weight distribution of the car. Most of the car's weight is on the front two tires.

These recommendations are for normal driving conditions. The pressures listed here would not be optimum for 1/4mi runs or at the AutoX track.

[SvenHoek]

Over-inflated at that pressure? Absolutely. Additionally, the wear pattern looks a bit like the tire being dragged from a bad toe adjustment. What is the actual measurements on your alignment? Often times "in the green" isn't actually good enough. I blew through a set of Yokohamas in under 5000 km with an alignment "in the green". Get the printouts if possible. If you're dog tracking, combined with the higher pressure, that pattern may result imo.

Also, this also really ought to be in "problem reports" rather than here. Just saying.

[fast gt]

42psi? what is the max pressure?

[MitsubishiOwn]

Originally Posted by fast gt

42psi? what is the max pressure?

Probably 44.

[lyonstl]

Originally Posted by fast gt

42psi? what is the max pressure?

I think on mine max pressure was like 51 or 52.

[Jemuel]

@Silvertune: The front tires have normal tire wear, a lot of people told me it could be bad rear struts but they don't have too much miles yet.

@fast gt:: Max tire pressure is 44


@SvenHoek:I will go and get the print outs, the last alignment check I got I remember the line being almost perfectly in the middle. I don't know what's the actual measurement, I'll try to get another alignment check and see what it is.


I lowered the tire pressure, I have 34 in the front and 31 in the rear. I'm going to drive it around and see how it feels and I'm also going to try to get an alignment check soon and post it here. Thanks for all the help.

[fast gt]

Wow you pretty much had them on max

Sent from my N860 using AutoGuide.Com Free App

[Bitter]

Just high tire pressure alone won't cause feathering, either bad struts or a toe issue or if you have worn parts allowing the tire to move when you're driving (bushings or bad toe links) that will cause feathering. The alignment can be all green with worn out shit, but as soon as the car comes off the rack it's all out of whack again.

[Chad]

Originally Posted by Bitter

Just high tire pressure alone won't cause feathering, either bad struts or a toe issue or if you have worn parts allowing the tire to move when you're driving (bushings or bad toe links) that will cause feathering. The alignment can be all green with worn out shit, but as soon as the car comes off the rack it's all out of whack again.

Jordan's right. High pressure causes inside tire to wear. Feathering (also known as scalloping) can only be caused by either A) Alignment is out/play in steering or suspension. B) You're not rotating your tires enough. Every other oil change.

[Jemuel]

Just wanted to update in case anyone else is having the same issue.

I rotated the tires and lowered the tire pressure as advised, an that seems to have fixed the problem.

Thank you all for your help.