thumping noise from tires

[varunk]

Hi, I have a 05 GA and whenever I go over choppy roads (roads that are not evenly leveled; some concrete roads have periodic ridges sort of) I can hear a very distinct thumping noise from coming through the tires (I guess all 4) as they go over the ridges. But this goes away once I am on smooth leveled roads. I do maintain the correct pressure 30-33psi. Is this expected or could there be some problem with my car?

Thanks!

[Eden]

Your tires might be aligned wrong, that will cause thumping at high speeds, but it might just be because of the roads.

[carlover626]

Probably the roads.
Try this, get out of your car around some of these places this happens and listen as other cars drive over the road. I bet you will hear the same sound.

[rixGAphx]

'Bad Alignment' rarely, if ever, causes a noise problem.
It causes at 'pull' to one side, or makes the handling feel 'squirrely', or creates strange wear patterns on the tires (usually near the shoulders).

But regardless of the road surface, 'bad alignment' doesn't cause any noise unless there is something else so wrong/broken that the vehicle can't be driven.
* * *

Bad 'tire balance' can cause some slight noise, but not from the tires themselves.
Rather, it sets-up a 'harmonic vibration' that kinda shudders thru the vehicle, causing rattles or general vibration that you can feel and sometimes hear.

This generally happens between 50 and 65 mph, since that is the 'sympathetic' frequency at which unbalanced passenger
car tires flex poorly and resonate with the springs.

But still, no 'thumping' kind of noise from the tires.
* *

I agree with carlover, that the noise is probably a function of the road surface causing the same kind of noise for most car tires.
* * *

Many car tires come with a 'free' 5000 miles balance and rotation.
Go to your tire store and have this done, especially if it's been over 10k miles. It's necessary maintenance, and actually saves you money (in longer tire life) even if you have to pay.
The tire technician can tell you if there is a wear pattern indicating poor alignment, plus balance the tires/wheels and rotate them for maximum milage (our fwd cars wear MUCH faster in the front).

Hope this helps.
-Rick

[varunk]

Rick, That does help. Since I got my GA from a dealer (and it is still under factory warranty), should I be going to the dealer for tire related issues? (As I do not know which tire store..)

[carlover626]

You can take your car to any tire shop for advice, but if they start telling you that things need replaced (other than your tires), go to the dealer.

[rixGAphx]

In general, tires on a new car are tricky relative to warranty.

The tires were bought in Detroit by Pontiac, and the tire manufacturer gave Pontiac (and you, as the buyer) a limited warranty relative to tread life.
Pontiac put those round rubber things on metal rims that Pontiac bought from somebody else.
Then Pontiac balanced the metal and rubber.

1. First go to Pontiac, and have them take a look.
* If there is something grossly wrong with the rubber:
* * They may handle the problem right there.
Or,
* * They may have an arrangement with one of the local dealers of that brand of tire (Goodyear, Goodrich, whomever), who handles the warranty-based claims of tires on Pontiacs under warranty.

* If Pontiac doesn't observe a problem, at the very least they should tell you who to go to for warranty claims on tires.

2. Do NOT go to a tire shop for a warranty claim on new-car tires.
* They will not get a DIME from the tire manufacturer.
* They'll just try to charge you for the balancing/rotation, and/or sell you a couple new tires.
* * *

But as Carlover and I said before, there prolly is NOT an issue with the tires relative to your current thumping noise.
It's prolly just a function of the road surface.

So whomever you take this problem to is going to be somewhat bothered by your complaint.
They'll either tell you 'it's normal', or charge you as much as you want to spend, looking for a problem that can't be found.

In the paper last week here in Phoenix, I saw a 'special' from a Pontiac dealer.
IIRC, they wanted about $29.95 for rotate/balance.
This seems about right.

Hope this helps.
-Rick

BTW: My '96, with 215/50-16's and only me as an occupant and no luggage, 'feels' best to me at 36 psi cold.
You could try this higher pressure for a week or so, and see if it affects the sound.

[varunk]

I run it at 34 cold (the max on my tire is 45) and definitely feel the difference from when I used to run at 30 cold.