Plop plop sound from tires - but not a flat!

Something stuck in the tire or tread?

 

Is there a nail or screw in one tire? Wheel bearing? Warped rotor?
Could be a few things. Drive in a parking lot and have someone along side and look and listen....

 

Have you inspected the entire circumference of the tires to discover any possible foreign objects lodged in the tread?

 

If it isn't something in the treads, once I had a stone in the metal hub that would drop and sound like that as the wheel turned at slow speeds. It finally fell out (and I found it - pea sized only), but I did a lot of head scratching before that because the treads were clean.

 

Tire probably bulged on the inside, had that happen to me before. Tires were about 7 years old at the time and I scraped the cement bump thing at the store parking lot that tells you to stop pulling forward in the parking space.

 

If the sound goes away by itself, it may have been a flat spot from being parked too long. It happens.

 

rotate the tires and see if the sound changes

 

I will add a possibility: You may have the beginning of tread separation between the outer layer of the carcass or belts and the inner layer of the carcass. You usually cannot see the bulge at rest, but when moving the separating spot flies outward a bit and then flops into the pavement as it comes down , causing the “plop” sound. If that goes on for a while you may see a slightly more worn spot in the tread where it is plopping against the pavement, but it is extremely dangerous to drive a tire that is having carcass layer separation as the stress at highway speeds can cause a sudden total separation and blowout. That has happened to the car I was driving and to a semi driving directly in front of me. In both cases the tire throws chunks of tread and the belts out in all directions and then the carcass explodes as it is too weak to hold the pressure. Please have it checked.

 

A wheel weight might have come off. Are they stick on ones?

 

I'm also leaning toward this theory/guess. The bulged sidewall on mine was on the inside sidewall,never knew it was there till the tire shop told me it needed to be replaced.

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That’s a possibility, but for me losing a tire-balancing weight has resulted in a weird vibration that would maximize at some lower speed like 30, but then decrease until hitting a higher multiple of that speed like 60 where it would increase again. So the vibration would not increase linearly with speed like the tread separation “plop” thing tends to do. That said, when you have two dynamically out-of-balance tires in the front, they can get “in phase” with each other at certain speeds , and in the Mazda I had with that problem the steering wheel would rather quickly shake so violently that car would become essentially directionally uncontrollable—very unpleasant.

 

a repetitive scraping sound as the rotor and pad rub

 

And it should pulse the brake pedal if you stop on mechanical brakes (switch to Neutral before you brake lightly),

 

I had some Goodyears that made a sound but there were pretty old. I tend to not rotate tires so they can stay on the rear without much wear for a long time.

 

I would check the play on your hub bearing. Jack up the car and see if there is play in the wheel. I would put money on that.

 

wheel bearing?

 

Maybe pop the wheel off and have a real close look.