Low Speed Shake after Changing to All Season Tires

[CWizard]

I recently replaced the stock Pirelli PZ4 summer tires on the Dark Horse with Pirelli P Zero AS Plus 3 (all seasons) for the winter. The PZ4s had about 5600 miles on them and gave a very smooth ride. The Pirelli all seasons were mounted on the stock wheels and balanced using a Hunter Road Force machine. During the first drive I noticed a new vibration felt in the seat - sort of a low frequency shaking at low speeds, very obvious around 30-40 mph. Feels like the rear of the car is slowly bouncing from side to side. No steering wheel vibration. Tire dealer suspected a bad rear tire, so the rear tires were replaced. There was no change in the drive quality - still felt seat shaking. Also, there is no obvious damage to any of the wheels.

Tire guy then rebalanced all 4 tires including matching high point on wheels to low point on tires. Same result, still felt shaking in seat. Tire dealer service manager drove car and agreed there was an issue, for which I was grateful, since I'm pretty picky about my cars and it would have been easy for him to say it all felt normal.

So...we replaced all four Pirellis with Continental Extreme Contact DWS 06 Plus tires, also all season. Same result.
Help!
Anyone else have a similar problem with all season tires?
FWIW, I did a rough check and both rear tires appear to have radial runout of about .060". Too much?
Thanks!

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[Skye]

I'm using Michelin A/S 4s and have never had a vibration.

Are the tires at the right pressure? I've noticed from my experience and other posts, companies often fill the tires way over, to like 40 psi, 2.75 bar.

Are the wheels torqued to the right spec? This should not make a vibration, but you never know. The rims should be seated and torqued in the star pattern to 150 lb-ft, 204 nM.

The only other thing I can think of to help troubleshoot is swap the front and back wheels/tires, like you're doing a rotation. See if the problem moves. Or if it is felt on one side.

 

[CWizard]

Wheels are properly torqued (did it myself to be sure). I'll recheck pressure. No sure about swapping front to rear since they're different sizes (255/40x19 F, 275/40x19 R).

 

[smurfslayer]

were they road force balanced, or just throw weights on and hope for the best?
The bigger & heavier the tire, the more prone they are to being out of round. It’s most pronounced on big àss off road tires, but can happen on some low profiles.

If the tire pressure isn’t goofy, wheels torqued correctly, maybe go back to the old tires and verify you don’t have the issue with those tires. Maybe you bent a wheel?

hit a pot hole or similar recently?

 

[CWizard]

Yes, they were road force balanced. Cold tire pressure is correct, 32psi. Hidden wheel damage is a possibility. I'm taking it back to the tire dealer tomorrow for another inspection and road force check. I'll get the road force numbers this time. The service mgr thinks it may be something inherent in the rubber compound that would cause all season tires to be less smooth than the Ford stock PZ4 summer tires. Seems like a stretch to me, but he continues to work with me to investigate, so far at no cost.

 

[smurfslayer]

The Pirelli all seasons were mounted on the stock wheels and balanced using a Hunter Road Force machine.

Duh! I missed this in your original post. It just goes to show: I’m so poor I can’t even pay attention.

anyway, IDK if we have a tire issue here. You’ve been 2 sets on the same wheels and both exhibit the same symptoms. I’d have the wheels checked for being true & run out.

I’ve bent 2 wheels on my wife’s Lincoln, one of them was minor, but the 2nd one was a 60mph impact on a pothole that had to be 6” deep with a sharp edge. I’m surprised it held air, the rim outer edge was destroyed. I replaced that wheel, but the original one causes a vibration you feel at about 55-60 and up. It’s not severe but it’s there.

good luck with the troubleshooting.

 

[SQJ]

I recently replaced the stock Pirelli PZ4 summer tires on the Dark Horse with Pirelli P Zero AS Plus 3 (all seasons) for the winter. The PZ4s had about 5600 miles on them and gave a very smooth ride. The Pirelli all seasons were mounted on the stock wheels and balanced using a Hunter Road Force machine. During the first drive I noticed a new vibration felt in the seat - sort of a low frequency shaking at low speeds, very obvious around 30-40 mph. Feels like the rear of the car is slowly bouncing from side to side. No steering wheel vibration. Tire dealer suspected a bad rear tire, so the rear tires were replaced. There was no change in the drive quality - still felt seat shaking. Also, there is no obvious damage to any of the wheels.

Tire guy then rebalanced all 4 tires including matching high point on wheels to low point on tires. Same result, still felt shaking in seat. Tire dealer service manager drove car and agreed there was an issue, for which I was grateful, since I'm pretty picky about my cars and it would have been easy for him to say it all felt normal.

So...we replaced all four Pirellis with Continental Extreme Contact DWS 06 Plus tires, also all season. Same result.
Help!
Anyone else have a similar problem with all season tires?
FWIW, I did a rough check and both rear tires appear to have radial runout of about .060". Too much?
Thanks!

I’ve been having a similar problem with the Pirelli P Zero AS Plus 3. Put on for fall driving on my 24 GT PP, no magnaride, vert. Have vibration bwtn 67-72 mph. Nothing before, nothing above. Had Ford dealer balance, still did it. Had outside source balance, still did it. Tire pressure all good, torque all good. Waiting for spring to put the original tires back on and see if it stops.
If you figure it out, please let me know.

 

[CWizard]

I recently replaced the stock Pirelli PZ4 summer tires on the Dark Horse with Pirelli P Zero AS Plus 3 (all seasons) for the winter. The PZ4s had about 5600 miles on them and gave a very smooth ride. The Pirelli all seasons were mounted on the stock wheels and balanced using a Hunter Road Force machine. During the first drive I noticed a new vibration felt in the seat - sort of a low frequency shaking at low speeds, very obvious around 30-40 mph. Feels like the rear of the car is slowly bouncing from side to side. No steering wheel vibration. Tire dealer suspected a bad rear tire, so the rear tires were replaced. There was no change in the drive quality - still felt seat shaking. Also, there is no obvious damage to any of the wheels.

Tire guy then rebalanced all 4 tires including matching high point on wheels to low point on tires. Same result, still felt shaking in seat. Tire dealer service manager drove car and agreed there was an issue, for which I was grateful, since I'm pretty picky about my cars and it would have been easy for him to say it all felt normal.

So...we replaced all four Pirellis with Continental Extreme Contact DWS 06 Plus tires, also all season. Same result.
Help!
Anyone else have a similar problem with all season tires?
FWIW, I did a rough check and both rear tires appear to have radial runout of about .060". Too much?
Thanks!

Update: First, thanks for all the responses. Current status: No change. Two days ago the tire dealer checked both rear wheels and made small (.25 oz on both) weight changes. Final road force values were 11 lb drivers side, 10 lb passenger side. Radial runout was .009" DS, .006" PS, which I think are negligible. There was no evidence, visual or otherwise, that a rim was damaged. I was standing beside the techs throughout the process, asking questions. (The tech who was operating the machine drives a Roush Mustang!) Rear wheels only were checked because of the belief that seat vibration with no steering wheel vibration is almost certainly a rear wheel issue. All this resulted in no change in the shaking.
Again this vibration is most noticeable at low speeds, feels like the rear is very gently bouncing from side to side at a constant frequency. What else might cause this, maybe a Magneride suspension problem??

 

[robvas]

The service mgr thinks it may be something inherent in the rubber compound that would cause all season tires to be less smooth than the Ford stock PZ4 summer tires.

Have you tried another shop?

 

[CWizard]

Have you tried another shop?

Yes. Ford dealer has also checked wheel balance, also with a Hunter Road Force machine. Same result.

 

[robvas]

Yes. Ford dealer has also checked wheel balance, also with a Hunter Road Force machine. Same result.

Right, but it's obviously not a tire problem at this point. Why aren't they looking anywhere else?

 

[CWizard]

I haven't taken it back yet to ask them to look elsewhere. Will do that, possibly today.

 

[smurfslayer]

Right, but it's obviously not a tire problem at this point. Why aren't they looking anywhere else?

Gotta agree, I think we’ve safely ruled out wheel/tire at least in the rear. Driveline?

 

[Cucurú]

I used to Rock & Roll in my VW. Now I Shake, Rattle and Roll

 

[Bikeman315]

Gotta agree, I think we’ve safely ruled out wheel/tire at least in the rear. Driveline?

I’m thinking a huge coincidence between the new tires and the vibration. I’d look at the rear differential and suspension.

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