Tire balancing fiasco

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Not to knock anybody that has posted on this thread but that RFD is really nice but not worth it. I have had people with cars RFD and regular balanced and they same it is the same. A proper regular balance is as good as a RFD. By proper I mean with a new machine not some old school machine that is probably needs calibration. RFD can help sometimes but for the most part it wont.
 
The HUNTER is the way to go. And the proper use of it is why I drive 52-miles round-trip to a DISCOUNT TIRE shop that knows what it is doing. I bypass at least seven other DISCOUNT TIRE locations for this reason.

Had a similar problem with the (terrible) GOODYEAR RT/S on my DODGE Ram. I just go back every so often (but, now, with less than 30m on tires the belts are starting to shift and each tire needs MORE THAN 80-oz of weight; they're now pretty well junk).

First question I ask the tech is that I want the before and after numbers (ounces) on each tire/wheel combo. If they don't know even that, time to go on down the road. Always deal with the store manager, insist on it.

In Dallas:
JUD BRADY
1901 Dallas Parkway
Plano TX, 75093
(972) 267-1877
 
quote:

Originally posted by TheTanSedan:
The HUNTER is the way to go. And the proper use of it is why I drive 52-miles round-trip to a DISCOUNT TIRE shop that knows what it is doing. I bypass at least seven other DISCOUNT TIRE locations for this reason.

Had a similar problem with the (terrible) GOODYEAR RT/S on my DODGE Ram. I just go back every so often (but, now, with less than 30m on tires the belts are starting to shift and each tire needs MORE THAN 80-oz of weight; they're now pretty well junk).

First question I ask the tech is that I want the before and after numbers (ounces) on each tire/wheel combo. If they don't know even that, time to go on down the road. Always deal with the store manager, insist on it.

In Dallas:
JUD BRADY
1901 Dallas Parkway
Plano TX, 75093
(972) 267-1877


Thanks,Jud.
I've been to a shop with the latest Hunter machine twice.The owner balanced the tires.
Going back tomorrow to try again.
Check out the lastest in my Tire Rack thread.
 
Road Force Variation has been in the General Motors realm of things for several years now. GM has specs for Road Force for car tires and light truck tires, which are warrantiable issues on new vehicle warranties. Ford and others might be similar.

GM now handles the tire warranties of their vehicles (in normal factory warranty period) and has supply networks to support that with local tire suppliers. Therefore, if you have a balance/shake concern on a new GM vehicle, you take it to the dealer rather than the tire shop for that warrantiable situation (tire balance has always been warrantiable during a particular "first miles" period of the warranty (one time). This is where the RFV check comes in, if the RFV is out of spec, the dealer orders a new tire(s) and handles everything themselves.

To use the machines, the machine tells the operator what to do and when and how much. They can be operated in "regular" mode, but it's obvious when they are in RFV mode by the way they do things before the balance testing starts.

RFV used to not be an issue, but with most all cars now having independent rear suspensions, it can be an issue (the "heavier" or "worst" balance tires used to be placed on the rear axle as the heavier live axle would be harder to shake than the front tires and their independent suspension).

If the particular Ford wheels are aluminum (which I suspect they are), there are particular "coated" weights designed to be used on such wheels (although the rim configuration might look identical to that of a stamped steel wheel). "Coated" in a vinyl/plastic coating over a normal style weight of a particular shape.

When you watch the Hunter machine going through the RFV test, it'll show a "area" of where the problem is. I think that in prior decades, it was called a "hard spot in the tire" or could be where the belts/plies overlap? It's all lined out on the screen what the operator must do and then recheck to see if what was done "worked". It can result in the tire being broken down and repositioned on the rim, just like the non-RFV tire balancers have done for ages.

In the days of "Tire Matching", the paint daub or spot on the sidewall was supposed to be matched to the valve stem hole in the wheel, thereby putting the tire's "high spot" with the wheel's "low spot" for a better assembly, with respect to ride smoothness. I'm not sure if any of the younger generation of tire shop employees know to do that.

Enjoy!
CBODY67
 
Good post, CBODY67!

Allow me enhance it.

GM's "spec" for tires and wheels is based on a particular measuring technique. Unfortunaely, the machines that perform this technique are expensive (~$600,000!)

The Hunter GSP9700 does something similar, but not exactly. So "spec" isn't quite the term to use when using the Hunter machine.

For example, the Hunter machine uses either a 7" or a 14" diameter wheel, while the road surface is basically flat. The machine tends to emphasize localized variations and downplays variations spread over a large area. So you can get both false positive (The machine say OK, but it's not) and false negative (The machine says not OK, but it is!)

Also, ply and belt splices aren't the major contributor to road force variation. That means you can have HUGE!! splices and still have a tire that rides good. (BTW the largest contributor to road force variation is tread thickness variation, and unless you have X-ray vision, you won't be able to see this!)

What has also changed over the years has been the stiffness of the chassis's. This has moved the resonant frequencies into the area where tires resonate! This can cause huge unfixable vibration Problems. GM has had several of these! (Ford, too!)

Hope this helps.
 
Thanks for the additional comments. In the dealership realm of things, with GM now having tires in the vehicle's basic warranty coverage, if the Hunter machine indicates that the tire's road force variation is not within the GM specs (from the appropriate TSB, for cars and light truck chassis vehicles), then the dealer orders a new tire(s) as necessary until the issue is "in spec". Each tire manufacturer also has some criteria for what they'll cover and not cover, though, regarding how long the tire has run before the RFV is checked.

According to a Goodyear rep, they don't have and will not honor a warranty claim for "road force variation", but call it "ride disturbance" instead. Another manufacturer states that the tire must have 500 miles on it before they will cover a RFV claim. But that is "them" talking and not "GM", per se.

I understand the relationship of the size of the drum that measures RFV on the balancer and how it might not completely relate to how the tire flexes on an actual roadway. I supposed that as long as the measuring technique is standardized (and the equipment is so calibrated), then the size of the rolling/bead seating drum would not be as critical. It's not that it is supposed to simulate the actual road surface, but that it's done in a standardized manner.

I concur that chassis stiffness is greater than it used to be, but I feel the issue is more in the weight of the tires versus the weight of the wheels they are mounted on being, generally, less than what they used to be in the 1970s (for example). It used to be that an H78-15 bias ply tire would have enough Fed Excise Tax on it to indicate a weight of 28-30 pounds. Now, if you can find the weight of the equivalent P225/75R-15 modern radial tire, it'll probably be more like 25 lbs. Not to mention the generally higher inflation pressures now used for fuel economy reasons. All of these things do change the resonant frequency of the tire itself, to a certain degree.

In the original radials, it was that resonant frequency (in the "boom" lower frequency spectrum) that resulted in more noise in the 45mph range on unit-body construted vehicles, but once the vehicle speed rose into the 50+mph range or slowed below the 40mph range, things got much smoother and quieter. Body/frame construction vehicles were less sensitive to these things, due to their greater isolation of the frame from the body structure. Of course, the resonant frequency was demonstrated to be different between different tire brands/models and how they interacted with the vehicle they were installed upon.

In modern times, the majority of cars are unit-body construction, reinforced to comply with Federal Safety crash criteria. Strut suspensions have replaced control arm suspension, typically, and have different ways of dealing with suspension compliance and noise transfer. Many suspension pieces are "light allow" rather than stamped steel, as are some of the front subframes on many fwd cars.

And, now, we have the trend toward tires of even larger diameters and shorter sidewalls. Less flex in the tire makes tire construction concerns much more critical. Less sidewall height means less room for road impact energy to be absorbed and/or dispersed. Add in the "tread caps" to make the tread itself stiffer, and that figures into the mix too.

I remember when the old Atlas Plycron tires (circa 1963+), say in 7.75x14 size, would balance with not more than .5 ounces of weight on each wheel. If they took more than that, something was wrong! Usually, they took less.

And the trusty bubble balancer, if the operator knew how to use it "right", worked fine for all but the most difficult balance issues. For something better, there was the Stewart-Warner Alemite spin balancer that spun the tire "on the car" to balance the complete rotating assembly at whatever speed the operator desired (depending on how long he kept the drive wheel held against the tire!). If you pulled the tire off for any reason, you marked the lug stud that matched the valve stem location so that the original balanced relationship could be maintained.

Things are different now, but I guess we're lucky that things work as good as they did (back then) and do (now).

Enjoy!
CBODY67
 
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