Potholes and shaking tires

[grampi]

I have to wonder if there's a connection between potholes and tires that would lead to a steering wheel shake. Between last summer and fall I had to replace both of my front tires. The ride was smooth, but over the winter I noticed the steering wheel taking on a shake at highway speeds, not bad, but bad enough to be annoying. I took the car back to Discount Tire (where I bought the tires) and had them rebalanced. Didn't help. So over the weekend I rotated the fronts to the rear and rears to the front. Problem solved, as the shake isn't noticeable with these tires on the rear. Only thing is, I have no idea what's causing the shake with those particular two tires on the front. It wasn't a balance issue, so what else could it be? Is it possible for tires to be damaged in such a way by pot holes that they look and roll normally, but the damage is only noticeable at highway speeds? I don't know what else would cause tires that are still fairly new to shake like this.

 

[901Memphis]

Possibly a bad balancing job even after they re balanced them is my only thought. Do they use road force balancing? That's what you need.

 

[grampi]

Originally Posted By: 901Memphis
Possibly a bad balancing job even after they re balanced them is my only thought. Do they use road force balancing? That's what you need.


No idea, never heard of it...they didn't charge me anything for the rebalance, is that something they'd do if they were doing the road force balancing?

 

[Volvohead]

Might be a bad tire on that axle.

Ask them to RF balance them.

That has helped weed out a bad tire (radial pull,etc.) that a regular balance just doesn't catch. Otherwise, you can rotate them around to isolate the culprit.

Unless this is on a finicky rear end, I'd wait another month or so. The potholes are still really bad this year, and many are tire-killers.

My wife managed to whack the biggest pothole in town this weekend, two days after a new tire install with alignment. Fortunately, nothing was harmed. But the same hole took out two tires on a Pathfinder two weeks ago. It still sits there gaping, like a hungry waiting shark, even though the whole town knows about it.

 

[Rand]

There was a car eating pothole up by cleveland today..

saw ton of cars sitting there with blown out tires.

Could be uneven wear on the tires or tire(s) going bad.

run your hand back and forth in both directions on the tread to see if it has uneven wear.

A roadforce balance will tell you if the tire is bad, or the balance is bad.. ask for a printout of the road force variation if possible.

http://classic.artsautomotive.com/GSP9700.htm

has abit of info on it you might want to read. Seems mostly correct with nice pictures.

 

[eljefino]

Yeah you can damage the tire's internal structure so it's round but "soft" in one spot and hard in another. This tends to show up at around 45-50 MPH. As said above, road force may be the cure.

Ask if you can see them spin your tires as well; you could have a bent rim or a visibly egg-shaped tire.

 

[CapriRacer]

Originally Posted By: grampi
I have to wonder if there's a connection between potholes and tires that would lead to a steering wheel shake. Between last summer and fall I had to replace both of my front tires. The ride was smooth, but over the winter I noticed the steering wheel taking on a shake at highway speeds, not bad, but bad enough to be annoying. I took the car back to Discount Tire (where I bought the tires) and had them rebalanced. Didn't help. So over the weekend I rotated the fronts to the rear and rears to the front. Problem solved, as the shake isn't noticeable with these tires on the rear. Only thing is, I have no idea what's causing the shake with those particular two tires on the front. It wasn't a balance issue, so what else could it be? Is it possible for tires to be damaged in such a way by pot holes that they look and roll normally, but the damage is only noticeable at highway speeds? I don't know what else would cause tires that are still fairly new to shake like this.


Very likely you have an alignment problem that is causing irregular wear in the tires, which in turn is causing a vibration. In other words, the tire is no longer round.

Is this caused by potholes? Perhaps. But if you don't fix the alignment, eventually you'll wear the other tires into an out-of-round state, and the vibration will be back. But this time, rotating the tires won't solve the problem because it is unlikely the previous pair will have worn off the irregular wear that was there previously.

Do you know which end the out-of-round tires are on now? You can tell by where the vibration came from. If it was the front tires, the vibration would be in the steering wheel, and if it was the rears, the vibration would be in the seat.

Also, you did rotate tires regularly, didn't you? Even vehicles "within spec" can wear tires irregularly if the tires stay in one position too long.

I am of the opinion that published vehicle alignment specs are too wide - by half. The alignment needs to be within the inner half of the tolerance for there to be good tire wear.

And lastly, some vehicle's alignment specs are for handling, not tire wear - camber setting. Anything over 1° is excessive - IMHO.

 

[grampi]

The "out of round" (or whatever) tire(s) causing the steering wheel vibration are now on the rear and the vibration is no longer felt. So let me see if I can get a handle on road force balancing. I'm guessing this isn't the usual way they balance your tires? Also, if spin balancing the tires doesn't work, why do they still do it? Why isn't road force balancing the way they balance all tires now? I guess I don't understand why they have two different methods of balancing tires...

 

[Volvohead]

Originally Posted By: grampi
The "out of round" (or whatever) tire(s) causing the steering wheel vibration are now on the rear and the vibration is no longer felt. So let me see if I can get a handle on road force balancing. I'm guessing this isn't the usual way they balance your tires? Also, if spin balancing the tires doesn't work, why do they still do it? Why isn't road force balancing the way they balance all tires now? I guess I don't understand why they have two different methods of balancing tires...


Cost. RF is a relatively more recent technique. Commercial balancing stations are not inexpensive. Many tire shops still don' t have RF balancers. RF balance is more expensive to the consumer, and most consumers are fine with standard balancing.

Surprisingly, the best bet to find a shop that offers RF is higher end car dealers.

 

[javacontour]

Perhaps a bad tire.

I posted this in my Conti DWS thread.

http://s960.photobucket.com/user/tbright1965/library/Conti_PIcs

It shows a tire damaged by a pot hole. That was the last straw, my tires seems to be magnets recently, picking up every sharp shard of metal, so I decided on new tires this spring rather than repair the repairable and try to make it to fall.

So it's possible it's a damaged tire causing issues.

 

[AboutTires]

There are a couple of possibilities here: You most probably have a bent wheel or a bent steel belt in the tire. It's probably not alignment because it went away when you moved the front wheels to the rear. You know it was in the front, but just because you don't feel it from the rear doesn't mean it's gone away. Here's some resources.

http://tires.about.com/od/wheel_safety_maintenance/a/Diagnosing-Wheel-Vibration.htm

http://tires.about.com/od/Tire_Safety_Maintenance/a/The-What-Why-And-How-Of-Wheel-Balancing.htm

http://tires.about.com/od/Tire_Safety_Maintenance/a/Help-My-Car-Shakes-And-Nobody-Knows-Why.htm

http://tires.about.com/od/Tire_Safety_Ma...nd-Remedies.htm

 

[grampi]

Originally Posted By: AboutTires

There are a couple of possibilities here: You most probably have a bent wheel or a bent steel belt in the tire. It's probably not alignment because it went away when you moved the front wheels to the rear. You know it was in the front, but just because you don't feel it from the rear doesn't mean it's gone away. Here's some resources.

http://tires.about.com/od/wheel_safety_maintenance/a/Diagnosing-Wheel-Vibration.htm

http://tires.about.com/od/Tire_Safety_Maintenance/a/The-What-Why-And-How-Of-Wheel-Balancing.htm

http://tires.about.com/od/Tire_Safety_Maintenance/a/Help-My-Car-Shakes-And-Nobody-Knows-Why.htm

http://tires.about.com/od/Tire_Safety_Ma...nd-Remedies.htm


I can rule out a bent rim...I would've known about anything that happened that was enough of an event to bend a rim, so I am leaning towards it being a damaged belt...

 

[Papa Bear]

Originally Posted By: grampi


I can rule out a bent rim...I would've known about anything that happened that was enough of an event to bend a rim, so I am leaning towards it being a damaged belt...


Are you the only person who drives that vehicle?
If others drive it then "you don't know everything".

 

[datech]

Originally Posted By: Volvohead
Originally Posted By: grampi
The "out of round" (or whatever) tire(s) causing the steering wheel vibration are now on the rear and the vibration is no longer felt. So let me see if I can get a handle on road force balancing. I'm guessing this isn't the usual way they balance your tires? Also, if spin balancing the tires doesn't work, why do they still do it? Why isn't road force balancing the way they balance all tires now? I guess I don't understand why they have two different methods of balancing tires...


Cost. RF is a relatively more recent technique. Commercial balancing stations are not inexpensive. Many tire shops still don' t have RF balancers. RF balance is more expensive to the consumer, and most consumers are fine with standard balancing.

Surprisingly, the best bet to find a shop that offers RF is higher end car dealers.


If you haven't read that article about the Road force balancing it's well worth reading. There is a link to the company that makes the machine, hunter.com I think. On their web site they have a locator link you put your zip code in and it lists shops in the area with the various machines they have.

 

[AboutTires]

Originally Posted By: grampi

I can rule out a bent rim...I would've known about anything that happened that was enough of an event to bend a rim, so I am leaning towards it being a damaged belt...


While I'm not doubting you personally, I truly cannot tell you how many times I've heard those exact words from smart and reasonable people who turned out to have bent rims. Don't necessarily rule it out on that basis.

 

[CapriRacer]

Originally Posted By: grampi
The "out of round" (or whatever) tire(s) causing the steering wheel vibration are now on the rear and the vibration is no longer felt. So let me see if I can get a handle on road force balancing. I'm guessing this isn't the usual way they balance your tires? Also, if spin balancing the tires doesn't work, why do they still do it? Why isn't road force balancing the way they balance all tires now? I guess I don't understand why they have two different methods of balancing tires...


Grampi,

First "RoadForce Balancing" isn't balancing. It's runout matching - and the process is matching the high point runout of the tire with the low point runout of the wheel such that the overall assembly is "rounder". The proper term is "Match Mounting".

Wny don't they do that all the time? Because 90% of the time, it isn't required. It also means the tire shop has to buy a $10K+ machine and have someone trained to use it. In most part of the country, regular dynamic balancing is adequate, but every so often a problem will come up, that can be solved by match mounting. Just be aware that not ALL situations can be fixed with balancing and match mounting. Irregular wear can either be so bad that it can't be fixed, or the wear pattern may be a harmonic (higher frequency than balancing can take care of.)

Second, "damaged belts" almost don't exist. It's a commonly used phrase mistakenly used where "irregular wear" would be the proper diagnosis.

As I said, you have an alignment problem that might be aggravated by insufficient rotation practices. So unless you deal with that, the problem will be back.

 

[grampi]

Originally Posted By: Papa Bear
Originally Posted By: grampi


I can rule out a bent rim...I would've known about anything that happened that was enough of an event to bend a rim, so I am leaning towards it being a damaged belt...


Are you the only person who drives that vehicle?
If others drive it then "you don't know everything".


Yes, I'm the only driver of this vehicle...

 

[geeman789]

Think of this example. You have a slightly bent wheel / tire assembly, and you take it in to get balanced. The shop can usually get the "balance" pretty close, as in the center of gravity (cg) is in the exact middle of the wheel. So the tire is "balanced". It will still vibrate rolling down the road, because the wheel is bent, and there is a hop. If you took it back to be re-balanced, it would spin up as being "balanced"' but it is not " round..."

Road force balancing does two jobs. Yes, it will "balance" the assembly, just like any spin balance does. But the machine will also help "match" up the wheel and tire in the best possible position, the "roundest" assembly. EVERY wheel/ tire has some out of roundness, and road force balancing works well to match the stiff/high spot of the tire, with the low spot on the wheel, so the unit will be balanced and as round as possible.

Go look at a new car lot. Check out the wheels/tires. You will usually see a green sticker or some sort of mark on the wheel, and you will usually see a red dot on the tire matched up to this spot. The car maker takes extra care to measure the wheels and test the tires, so they can be matched for the smoothest ride. That is why when you replace the factory tires, it can be hard to get as smooth a ride as the factory set.

Remember, "balanced" is not always smooth. If you "stack" the tolerances, ie you end up with the high /stiff spot on the tire matched with the high spot on the wheel, you might still have a vibration even with a perfect balance job. If a tire comes back with a vibration, shops without roadforce balancing equipment should check the balance again, and if it shows as "balanced" , then rotate the tire 180 * on the wheel and re-balance, Often, this takes care of the problem. If the tire guy says " I dont know, the machine says its balanced...?", GO SOMEWHERE ELSE...!

Some cars are more sensitive to out of round / balance issues, and the front axle is wayyyyyyy more sensitive than the rear, because the front has a moveable steering axis to transmit vibration, the rear does not. It takes a large imbalance/ out of round issue to feel it through the rear ( and your rear...!) , but not much in the front.

 

[geeman789]

Why dont all shops road force balance... ?

$$$. The machine is 3 to 5 times as expensive, way harder to use properly, and subject to much higher maintenance ... and takes longer etc.

As a previous poster mentioned, many cars run smoothly with just an accurate spin balance. Some cars, however, almost never do... and some tires are too out of round / too stiff in one spot , even brand new, to get to run smoothly...even if they are road force balanced.

And some drivers are more sensitive than others...!

 

[grampi]

Originally Posted By: geeman789
Think of this example. You have a slightly bent wheel / tire assembly, and you take it in to get balanced. The shop can usually get the "balance" pretty close, as in the center of gravity (cg) is in the exact middle of the wheel. So the tire is "balanced". It will still vibrate rolling down the road, because the wheel is bent, and there is a hop. If you took it back to be re-balanced, it would spin up as being "balanced"' but it is not " round..."

Road force balancing does two jobs. Yes, it will "balance" the assembly, just like any spin balance does. But the machine will also help "match" up the wheel and tire in the best possible position, the "roundest" assembly. EVERY wheel/ tire has some out of roundness, and road force balancing works well to match the stiff/high spot of the tire, with the low spot on the wheel, so the unit will be balanced and as round as possible.

Go look at a new car lot. Check out the wheels/tires. You will usually see a green sticker or some sort of mark on the wheel, and you will usually see a red dot on the tire matched up to this spot. The car maker takes extra care to measure the wheels and test the tires, so they can be matched for the smoothest ride. That is why when you replace the factory tires, it can be hard to get as smooth a ride as the factory set.

Remember, "balanced" is not always smooth. If you "stack" the tolerances, ie you end up with the high /stiff spot on the tire matched with the high spot on the wheel, you might still have a vibration even with a perfect balance job. If a tire comes back with a vibration, shops without roadforce balancing equipment should check the balance again, and if it shows as "balanced" , then rotate the tire 180 * on the wheel and re-balance, Often, this takes care of the problem. If the tire guy says " I dont know, the machine says its balanced...?", GO SOMEWHERE ELSE...!

Some cars are more sensitive to out of round / balance issues, and the front axle is wayyyyyyy more sensitive than the rear, because the front has a moveable steering axis to transmit vibration, the rear does not. It takes a large imbalance/ out of round issue to feel it through the rear ( and your rear...!) , but not much in the front.



I certainly understand all of this, but my tires always start out as smooth drivers....they become shaky after they've been on the vehicle for a few thousand miles. Problem is, I don't know if it's the pot hole covered roads I travel that's making them shaky, or if it's a problem with my vehicle. I guess I could have a 4 wheel alignment done and see if that cures the problem...