Please explain road force balancing

[RampantAndroid]

Hi all,

I have an Audi A4 that had a wobble going at highway speeds. Discount tire spin balanced it twice, but it didn't help any. Took it to the dealer and they road force balanced and while they said the spin balance was good, road force was off.

These are new tires (bought in december, 3k miles on them, new voxx rims as well.)

Why do I have this imbalance? Is something wrong with the tires? Why is the end balance not 0? (inked number is after balance, rf = right front, rr = right rear etc.)

Thanks!

 

[Corn]

Tires and wheels are not always perfectly round. Most times excessive road force can be dialed out bymatching the high spoton the rim with the low spot on the tire. Those numberslookbas for the rf and lr tires. Discounttire also has road force balancers and you should have them match the tires to the rims.

 

[Corn]

Actually after taking another look those numbers don't look bad at all. There is a lot of weight on those tires but the road force numbers look OK.

 

[RampantAndroid]

Actually after taking another look those numbers don't look bad at all. There is a lot of weight on those tires but the road force numbers look OK.

I still feel SOME vibrations, though I'm unsure if it's just the road now. Should I try to get discount tire to warranty the tires? Or could this be the rims?

RR looks like the 23lb is highlighted, I'm guessing that's bad? What do the dimensions in the lower left mean? Is one tire an inch bigger than the rest?

 

[SpatiallyAware]

Rotate the tires front/back and see if the wobble follows.

If it does, I would try and get them replaced. It will help if the dealer blames the tires.

 

[RampantAndroid]

Talked with Discount Tire, and as soon as I said it was off by 23lb before balancing, they ordered a new tire. They don't think I'll need a second new tire, but they will check tread wear when I come in.

 

[leper84]

Those tires are still pretty far out of balance for only 3k miles. Someone was sloppy, if we are going to take someone's money it damn well better zero out before it comes off of the balancer.

Road force matching isn't normally done with installation, and most places usually charge for it unless its a warranty issue (just like you're experiencing). As said, you rotate the tire on the wheel to match high and low spots to make the assembly more round as a whole.

They should be able to measure run-out and be able to tell you specifically whether it is the tire or wheel that is more out of round as well as how many pounds of force each are responsible for, as well as estimating force after matching. I know some of the Hunter balancers are damn impressive, they will even graph out the harmonics of the vibration. Anything around 20lbs of force is too much and can be anything from a bad tire, wheel, or the quality of the mounting surface for the bead of the tire.

Either whoever checked the road force was sloppy measuring the dimensions of each wheel or you have some weird new wheels. I'd drop it by Discount and make them check the road force of all four tires, measure the run-out of all four wheels, show you the results with your own eyes and explain them to you. They need to actually figure out what is going on before they throw tires at it. Did they sell you the tires and the wheels? If so they own any problems you have with it, considering the money you probably spent they need to kiss a little ass.

 

[RampantAndroid]

OK - Audi had told me it was common to get tires that couldn't hit zero...

In other news, Discount Tires has found out there are no more PA3s around, and that they will need to replace the whole tire set.

Except they're going to see what "refund michelin can give on the 4 tires" and then make me pay the rest. I am *NEVER* going back to discount tire *AGAIN*. I paid for the replacement certificate and now they want to **** me out of more money.

 

[SpatiallyAware]

I used to really like discount tire. But, they were a different company 10 years ago. They're essentially the walmart of tires at this point.

For the past 6-7 years I've done almost all of my tire shopping with an independent place. They do better alignments, better tire installs, their guys are better trained, and they are MUCH better about dealing with warranties.

Their prices are within 5% of costco.

I would call around performance shops and find out who does the best alignments, then buy your tires from there.

They can honor the general michelin warranty, so if you offer to buy your next set from them they'll probably help you out.

 

[RampantAndroid]

They can honor the general michelin warranty, so if you offer to buy your next set from them they'll probably help you out.

The problem is the Michelin warranty as I understand it doesn't help much here, unless their warranty says that if they cannot give you the same tire they'll give you a whole new set.

Also, I don't play to buy a new set of tires for another few years, more maybe since I switch between summer performance and winter performance tires. So I don't know how much that promise would matter to them.

My real issue is that Michelin won't cover all 4 tires, and neither will Discount Tire. In both cases they are unable to replace my tire, and I have AWD meaning they need to match my tires up.

 

[Pacfanweb]

Road force has a roller on the balancer that rolls against the tread measures whether the tire has the same resistance all the way around.

It too much difference, that would make the tire potentially vibrate.

Essentially, too little road force could basically cause the tire to compress more at that spot, or not compress enough at another spot. It'd be about like having a hard or soft spot in the tire.

 

[RampantAndroid]

Road force has a roller on the balancer that rolls against the tread measures whether the tire has the same resistance all the way around.

It too much difference, that would make the tire potentially vibrate.

Essentially, too little road force could basically cause the tire to compress more at that spot, or not compress enough at another spot. It'd be about like having a hard or soft spot in the tire.

I understand that much at this point, I think - but does a high imbalance allow a warranty replacement even if it isn't out of round? My tire seems to be round, but well off in terms of road force. Even once balanced I feel the vibrations.

 

[rommelrommel]

I understand that much at this point, I think - but does a high imbalance allow a warranty replacement even if it isn't out of round? My tire seems to be round, but well off in terms of road force. Even once balanced I feel the vibrations.

I've always heard that discount tire will replace them on the first balancing if the tires are too far out to be properly balanced. Not sure if it's warranty or if the tires go back as defective. If it's down the road I think it's your problem.

 

[phucheneh]

Explain road force balancing:

It is primarily a) a marketing gimmick and sometimes b) a method used to quantify exactly how shitty the rubber industry has become. It really has no impact on the customer, other than sometimes being a number cited when warrantying tires.

Anyone who talks about how it allows for optimal match-mounting of tires is full of crap. Wheels are round and do not have notable variations in density (not that the machine could measure the latter, anyway). Rotate an oval tire to any position on an unbent wheel and, surprise, your tire is still an oval.

So you're left with it just being a number. It is not the same as balance. Tires can be in balance* and still have a high road force number, which basically just indicates a significant amount of radial runout- 'road force' is the amount of force that the lopsided tire is thwacking the ground with every time it rotates. Significant lateral runout can be present with both 'perfect' balance AND a low road force number. Lateral runout, though, will usually only cause issues on the steering axle (this is where steering wheel 'shimmy' comes from). Your average felt vibration is generally a function of radial runout and/or imbalance.

*'in balance' meaning the machine says zero. I could put five pounds of of unneeded weight on a wheel/tire and get it to show zero on a balancer. It will still cause your teeth to be shaken out of your head. Even basic balance numbers are meaningless if the balancing is not done right. I.e. dynamic (not static) with one group of weights on each side of the wheel (no 'counterbalancing').

More important than all that, OP:

Your tire shop is incompetent and the dealer is lying. One of your front tires was out by about an ounce and a half. Most decent non-truck tires will take...about an ounce and a half of weight. They probably still don't have it right. Check your wheels for copious amounts of randomly-placed sticky weights. Most 'tire techs' are too retarded to pry off the old ones before putting additional ones on there.

Beyond that, their supposed 'after' road force numbers are fabricated bullshit. The one single wheel that was in balance went from 23lbs (pretty damn high) to 3lbs (unbelievably low) due to...what? What did they do? Fart magical pixie dust onto it?

 

[phucheneh]

Let me put this another way...if you have a choice between:

A) A mentally handicapped person balancing your tires with one of these

B) A competent person balancing your tires with one of these

Choose option B.

 

[michal1980]

Explain road force balancing:

It is primarily a) a marketing gimmick and sometimes b) a method used to quantify exactly how shitty the rubber industry has become. It really has no impact on the customer, other than sometimes being a number cited when warrantying tires.

Anyone who talks about how it allows for optimal match-mounting of tires is full of crap. Wheels are round and do not have notable variations in density (not that the machine could measure the latter, anyway). Rotate an oval tire to any position on an unbent wheel and, surprise, your tire is still an oval.

So you're left with it just being a number. It is not the same as balance. Tires can be in balance* and still have a high road force number, which basically just indicates a significant amount of radial runout- 'road force' is the amount of force that the lopsided tire is thwacking the ground with every time it rotates. Significant lateral runout can be present with both 'perfect' balance AND a low road force number. Lateral runout, though, will usually only cause issues on the steering axle (this is where steering wheel 'shimmy' comes from). Your average felt vibration is generally a function of radial runout and/or imbalance.

*'in balance' meaning the machine says zero. I could put five pounds of of unneeded weight on a wheel/tire and get it to show zero on a balancer. It will still cause your teeth to be shaken out of your head. Even basic balance numbers are meaningless if the balancing is not done right. I.e. dynamic (not static) with one group of weights on each side of the wheel (no 'counterbalancing').

More important than all that, OP:

Your tire shop is incompetent and the dealer is lying. One of your front tires was out by about an ounce and a half. Most decent non-truck tires will take...about an ounce and a half of weight. They probably still don't have it right. Check your wheels for copious amounts of randomly-placed sticky weights. Most 'tire techs' are too retarded to pry off the old ones before putting additional ones on there.

Beyond that, their supposed 'after' road force numbers are fabricated bullshit. The one single wheel that was in balance went from 23lbs (pretty damn high) to 3lbs (unbelievably low) due to...what? What did they do? Fart magical pixie dust onto it?

whatever.

I bought a set of wheels + tires from tirerack. They had a nasty wobble @ 75mph. They told me to find a road force shop to have them checked.

2 of the wheels 'failed' the road force balancing. and were fixed. wobble was gone. Tirerack paid for the service after faxing them the proof.

 

[phucheneh]

If the wheels were straight, your problem was fixed by balancing.

This is not opinion; this is fact. 'Road force' is not the voodoo that many make it out to be.

 

[Pacfanweb]

If the wheels were straight, your problem was fixed by balancing.

This is not opinion; this is fact. 'Road force' is not the voodoo that many make it out to be.

This is true. Road force and balance are different things. A road force balancing machine is just a balance machine that can also measure road force.

You can just do a regular balance on one without using the road force.


Road force is good for someone who knows how to operate the machine. You can certainly find a bad tire with one, but they are certainly not a catch-all. I've seen tires with acceptable road force still be bad, and I've seen ones that supposedly had unacceptable road force ride just fine.

It should be considered just another tool to test tires with, not a magic wand.

 

[rh71]

A Hunter9700 machine was unable to road-force balance my vibration at highway speeds away. Tried many regular balancers as well but they don't spin faster than 25mph so it was sort of pointless. The wheel was too out-of-round.

 

[RampantAndroid]

In further news about my tires:

Michelin has offered to give a full refund on the defective tire, but as the PA3 is no longer made and Discount Tire has none around, that's next to worthless. They offered a 55% refund on the other 3 tires.

My response to Discount tire was "well, then you're paying the other 45%" as the warranty that both Michelin and Discount Tire are "offering" isn't acceptable. Michelin clearly states they will cover 2 replacement tires if one is bad (from their website) - what the hell do I do here? If DT comes back with anything other than "here's a new set of tires" or "we found some PA3s lying around" I'm tempted to just use my legal plan from work to go at this - this cannot be legal (as replacing a single tire is certainly not in the spirit of the warranty at the very least.)

I wish I had gotten tires from Audi, they might cost more but they're less sleazy...

 

[hans007]

You don't have a 2009 or 2010 by any chance. Those had a suspension issue which Audi just kept telling people to road force balance over and over. Worst car company ever

 

[RampantAndroid]

You don't have a 2009 or 2010 by any chance. Those had a suspension issue which Audi just kept telling people to road force balance over and over. Worst car company ever

No, it's a 2014.

In the end, Discount Tire agreed to replace the tires. My set of PA3s is being swapped for Ice-x xi3 tires. They're H rated instead of V, but I think I can live with that (the PA3s failed to impress on snow. Maybe partially because I was on R18s, but whatever. I know the Xi3s do better on snow and ice.) My governor is at 130 already, and I don't want to hit that in winter so the speed rating doesn't worry me.

I trust it's the tire, not the suspension. Either way, the tire was highlighted as bad. Once I put the summer tires back on, I know they're good. If it still vibrates, I drop my problems at Audi's doorstep again.