Tire: tale of woe.
 

I have a Pro tour 66 Chevy pickup that I call a Cgt. Took about 2 years to build. Near the beginning of the build I bought a set of Pirelli Pzero tires 325/35/22 and 255/35/22 as I needed them to build the truck. But I have a problem with them. Started out as a vibration at 57mph. Nothing below and would go away after 58. Have had the fronts rechecked for balance. One of them they broke the bead and moved the tire on the rim. Needed half the weights to balance. But problem remained. Thought I would live with the issue but now in addition I get a sustained vibration after 70mph. Warranty was up before the build was finished and now with 1700 miles am wondering if new tires are the only answer? Anyone else have issues with Pzero's?[ATTACH]
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Have you tried a different set of wheel tire up front?

Did they road force balance or just spin balance?

Keep us posted if you swap tires and it goes away!

Jeff-

how old are they? Both purchase dates and DOT manufacturer date?

I don't know what model they are, per tire rack pirelli doesn't make a model in both those sizes. I looked at the 1st 325/35/22 pirelli tire i saw and they said "Workmanship & Materials Warranty:
Unlimited Time / Free replacement first year or 2/32" wear, then prorated until 2/32" remaining depth"

So if the tire dealer isn't helping with a warranty claim perhaps call pirelli.

That said, how does the vibration manifest? steering wheel, floor pan, etc.? maybe its not a tire.

Now that I have heard of force balance, I checked and no where near here.
Just spin balance. Had the fronts rechecked today and they look good. Rears are a little tougher to get out but will get them checked tomorrow. As I mentioned in the original post I bought these tires at the beginning of the build 2 years ago. No warranty left.

What makes you 100% sure its the tire?

Is it present at all tire temps? Had an issue with the front tire on my HD that was more prominent when as the tire heated up. Forced the dealership to replace after being balanced and it and it was gone.

Not 100% its the tires. But seems odd out of the blue with no other changes I get vibration over 70. Being that I had already had an issue with vibration at 57 mph that appeared to be tire related I guess my opinion was tainted.

Moving parts and high speed harmonics can make all sorts of weird stuff manifest....anxious to hear what it turns out to be...

Jeff-

Big job getting the rears out. Had them checked. Both spun nicely had about 6 oz. of weights, 3 oz. 180 degrees from one another. We took them off and both ended up with 1.25 oz. The rears look really good. I will get it back together and take for a spin. I am still suspicious of the one front.

6oz of weight & the material split @ 180° tells me they need to rotate the tire on the wheel & re-balance. Similar weights @ 180° seem like they'd be canceling the effectiveness of each other. I stopped doing wheel/tire work a LONG time ago but even w/the equipment we had back then, those that 'knew', knew it was not a good thing.

It was suggested & I would agree to it that you should try some alternative front wheels/tires & see if/what the difference is if you still experience the issue after the effort on the rears. I know it sounds/reads easier than it is in reality, but it sure would help narrow your investigation IMO.

BTW.... I understand 100% about the difficulty removing the rears. I had to pull my 16x10 steelies w/30" tall tires off of what was basically a stock rear track width & a frame rail ride height @ 4.5" on my '64C10.
What a PITA.