New tires causing rear bounce

[TTU19]

I bought some new tires a couple month ago. Got XD Rockstar 20" wheels and BF Goodrich AT KO2 275/60r20 tires. Ever since I got them when I reach 72mph +, there has been more bounce and vibration than ever before. They put 2 new tires on the back and still doing the same thing.

 

Do you think it could still be tires, or maybe something wrong with the truck? I dont know what to do now.

[newdude]

Have you had them road forced? Could have a bad wheel or two as well.

[CounterMeasure]

Have you had them road forced? Could have a bad wheel or two as well.

 

This. You can weight-balance a square, but it won't ride very well at all.

[TJay74]

Easy way to check the wheels is to dismount the tires and have them balance and or road force the wheels only. They need to be able to zero out with no weight at all. Then from there mount the tires back up if the wheels are good and make sure they zero the wheel/tire assembly out once again, I would also have them use the road force on that option as well.

[pm26]

The easiest way to check the tires for obvious out-of-roundness is to jack up the rear of the truck with the wheels slightly off the ground. Then place a piece of 2X4 close to each wheel, shift the transmission into neutral, and spin each wheel by hand with the wood block riding close to the tread of the wheel on the bottom. If you see more than about 1/8" up and down movement, you have an obvious out-of-round tire problem.

 

Most likely though, they balanced your wheels wrong. Happens all the time. I am absolutely amazed how many place are not capable of balancing the wheels correctly, especially larger diameter ones.

[Vic15]

What air pressure are you running?

[TTU19]

When I first got them, the front would vibrate really bad at the 72+ mph. Told them and they balanced again. Still didn't fix it. Then had them rotate and balance and the back was now vibrating at the speed. They replaced 1 back tire, still doing it. Then replaced both back tires again, still doing it. They put a lot more air in them and balanced with less weights. It's not doing it as bad, but still doing it.

 

Cold tire pressure is about 39/40, after driving they get up to 44/45. I looked online and I've seen people run anywhere from 35 up to 50 on these, so I'm not sure what is correct.

[BigBadSierra]

Honestly try having a different place balance them.. It may be a human issue as well.

 

At least you will know if it's them or the tires.

 

I know when I had my Duratrac's put on the tech was good because he took the time to grind the weights off a bit just to get it exactly balanced.

[TTU19]

Yeah, I may have to do that. Sadly with this ongoing problem along with other little stuff, I may look to trade it in soon. Humm..