I was mounting another set of wheels with r-compound tires today, and I noticed this bulging on the inner side wall of the rear tire when I took it off the car, there is no puncture in the tire and I haven't been loosing pressure, I didn't curb the wheel or anything, the bulging is on the inside anyway, anybody here has similar experience? or at least know what caused this? is it safe to drive on it? or it needs replacing?

 

Maybe some extreme flatspotting or early tread seperation... I have never seen anything like that really.

 

It's hard to tell from the picture, but I had something similar happen to my right rear tire two years ago. It started with a small bubble on the inner side wall, and after a few months, it spread to the tread surface. I had a bumpy ride for a few days until I repaced both rears- at 17,000 miles they needed to be replaced anyway.

Firestone/Bridgestone had a serious problem with ply/tread separation many years ago, but I thought they had solved those problems. Maybe not.

 

Probably a sidewall separation. I'd replace the tire ASAP, you should think of it as an engineered component of your suspension system.

 

Tire defect.

 

Hard to tell, is it a bubble or the belt package slipped? Either way, recycling time.

 

I also can't tell by the picture. It can be an impact damage and the bubble is where the belts are cut on the inside of the tire. Take the tire off the wheel and look at the inside. If it is cut where the bubble is that is what happended. If not the bead could have been ripped when they were mounted. Air escapes down the inside of the tire at that point and can cause a bubble.

 

I took the tire off the wheel today, the belt has totaly seperated from the tread on the inside, but once took the tire off the wheel it looked pretty distorted, not sure it's a defect in the tire or not, but this tire has seen some intense track days, it could be the heat or something.