It dawned on me that many don't understand how this affects the feel of a car.
When a Hunter 9700 measures 20 pounds of additional force as the hard spot comes around [hard spot between tire and road] it acts like an out of round or is an out of round in the tire's perfect circle.
This 20 pounds forces the tire up more against the spring! On a Q rear the spring is only 123 pounds per inch so the spring compresses 20/123=0.1626"............just like hitting a bump every rotation this high..........the time delay of the spring compression is retarded/enhanced by the shock compresssion rate [depending on the friction/stickson in the shock] and rubber seats.........generally the body on rises half the amount [0.08"]due to energy lost in friction .
http://www.tireuniformity.com/...t.htm
Radial forces increase as the square of tire speed.
http://www.informs-cs.org/wsc00papers/135.PDF
http://www.adams.com/news/even.....pdf
"the wheel is sent off to final trueing that brings the wheel back by fixing the minute bends or wobbles. WCC typically returns the wheel to 5 to 10/1000th of an inch, where factory tolerances are typically 15/1,000th of an inch radial runout. For comparison, 25/1000 of an inch roughly what can be detected by the eye."http://www.vwvortex.com/featur...shtml
Radial force imbalance
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AZhitman
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Just spent 1.5 hours Friday with the tech at Discount (manager) watching over his shoulder while he did my four wheels on the 9700....
He showed me ALL the capabilities of this machine - it truly is an incredible unit.
After all was said and done, he was able to balance ALL four tires to .01 to .04 oz, and I have one rim with .02 radial runout on the inside lip (hard to find replacement 99 chrome alloys). Each tire was adjusted to have no more than 4lbs of force each (2 at 4lbs, one at 3 and one at 1.5), they started at 14, 14, 16 and 5. This required turning the tires on the rims on three corners and was done at the expense of sacrificing some directional "pull". When I showed up, the arrangement was generating 26 lbs of "pull" to the right. (I thought it was the combination of heavily crowned roadways in Phoenix for runoff plus the effect of steamroller tires.) I now have 6 lbs of pull to the left, which after the past 3 days I'm very pleased with - Car no longer "pulls" at all, and I traveled well over a mile on I-17 at 65-70 mph in the center lane w/o touching the steering wheel.
I highly recommend (or second Dennis' recommendation) that you ALL find a shop that has one of these machines and have your tires radial force balanced - it's an education in itself.
He showed me ALL the capabilities of this machine - it truly is an incredible unit.
After all was said and done, he was able to balance ALL four tires to .01 to .04 oz, and I have one rim with .02 radial runout on the inside lip (hard to find replacement 99 chrome alloys). Each tire was adjusted to have no more than 4lbs of force each (2 at 4lbs, one at 3 and one at 1.5), they started at 14, 14, 16 and 5. This required turning the tires on the rims on three corners and was done at the expense of sacrificing some directional "pull". When I showed up, the arrangement was generating 26 lbs of "pull" to the right. (I thought it was the combination of heavily crowned roadways in Phoenix for runoff plus the effect of steamroller tires.) I now have 6 lbs of pull to the left, which after the past 3 days I'm very pleased with - Car no longer "pulls" at all, and I traveled well over a mile on I-17 at 65-70 mph in the center lane w/o touching the steering wheel.
I highly recommend (or second Dennis' recommendation) that you ALL find a shop that has one of these machines and have your tires radial force balanced - it's an education in itself.
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AZhitman
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One more reason I love Discount Tire.
Once they realize you're not "Joe Consumer" and you know something about tires (thanks Dennis!), then you get treated right.
We discussed load ratings, the ridiculousness of speed ratings in Phoenix, "warehoused" NEW tires, the new requirements proposed by COngress, etc etc etc.
Turns out the guy doing my tires drives an older BMW 850Csi... A kindred soul.
Once they realize you're not "Joe Consumer" and you know something about tires (thanks Dennis!), then you get treated right.
We discussed load ratings, the ridiculousness of speed ratings in Phoenix, "warehoused" NEW tires, the new requirements proposed by COngress, etc etc etc.
Turns out the guy doing my tires drives an older BMW 850Csi... A kindred soul.
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EZcheese15
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Yeah, those machines are awesome....I've used them before and they are truly amazing.
On another note, I took my tires once to get mounted and balanced at a local Firestone place. I told them I wanted them static balanced (had nice rims, didn't want them scratched), and the guy told me their machine didn't do that. I looked over his shoulder at the machine for a second and said "do you have any idea what that button with the 'S' on it does?" He said "uh, not really." I said "press that button before you balance the tires, that 'S' is for static."
Boy those guys looked dumb when I told them that.
On another note, I took my tires once to get mounted and balanced at a local Firestone place. I told them I wanted them static balanced (had nice rims, didn't want them scratched), and the guy told me their machine didn't do that. I looked over his shoulder at the machine for a second and said "do you have any idea what that button with the 'S' on it does?" He said "uh, not really." I said "press that button before you balance the tires, that 'S' is for static."
Boy those guys looked dumb when I told them that.
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AZhitman
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- Location: Surprise, Arizona
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That's why I ALWAYS stand around and watch WHENEVER I have my car in a shop.
Those that don't like it don't get my business.
Amazingly, showing up with your own eye protection, and being able to speak/interact knowledgeably about the procedure being performed has a profound impact on the quality of service you receive. Again, thanks to Dennis/DAE/others!!!
Those that don't like it don't get my business.
Amazingly, showing up with your own eye protection, and being able to speak/interact knowledgeably about the procedure being performed has a profound impact on the quality of service you receive. Again, thanks to Dennis/DAE/others!!!
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szh
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EZcheese15 wrote:On another note, I took my tires once to get mounted and balanced at a local Firestone place. I told them I wanted them static balanced (had nice rims, didn't want them scratched), and the guy told me their machine didn't do that. I looked over his shoulder at the machine for a second and said "do you have any idea what that button with the 'S' on it does?" He said "uh, not really." I said "press that button before you balance the tires, that 'S' is for static."
My dumb questions of the day: what is "static balancing" of a tire and how does it prevent scratching the rims?
(Particularly if it is activated with a button labelled "S" ... I assume that they still hve to "tighten" the wheel onto the machine, etc., right?)
Z
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EZcheese15
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szhosain wrote:My dumb questions of the day: what is "static balancing" of a tire and how does it prevent scratching the rims?
(Particularly if it is activated with a button labelled "S" ... I assume that they still hve to "tighten" the wheel onto the machine, etc., right?)
Z
Static balancing is balancing only the inner side of the rim. So wheel weights only go on the inner lip, not the outter lip. Now days though, with a machine like the Hunter, they can do dynamic balancing with stick-on weights that go on the outside edge of the rim, but on the inside of the lip. Which creates for a better balance, and you still keep from putting metal hammer-on weights on the outter lip.
one problem with discount tire is the tire guys(not the asst managers, who sell you tires) are paid min wage or just above. i've spent many years with a direct competitor to discount tire, and i earned more than double min wage with full benefits/bonus/retirement program, and i did not work on commission ever. the value of knowing a good tire guy is priceless. discount tire checks for a pulse, then pays a guy min wage to bust tires all day. beware. i worked with a hunter 9700 for quite a long time and some tire/wheel combinations cannot be matched to run smoothly. such combinations usually include chrome and cheap tires. the key is to spend money when you buy tires/wheels. dont go cheap. you're not just buying a name brand or a look, when you spend more at a good shop, you're almost always buying quality. i've handled literally hundreds of vibration problems and i can tell you that the easiest way to avoid the nightmare of the vibration gremlin is to find a good, honest tire shop, and make like pals with the most knowledgeable tire guy there. he'll steer you in the right direction and away from the cheap stuff. and if/when there is a problem, he'll take good care of you.
PS: dynamic balance also allows you to place weights on back side of rim, both at rim edge, and at a point closest to the outer face or the wheel(but still on the backside of the wheel). another automatic feature allows the user to "hide" wheel weights behind the spokes of the wheel so no weights are visible. this works quite well.
PS: dynamic balance also allows you to place weights on back side of rim, both at rim edge, and at a point closest to the outer face or the wheel(but still on the backside of the wheel). another automatic feature allows the user to "hide" wheel weights behind the spokes of the wheel so no weights are visible. this works quite well.
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Q45tech
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The problem with cheap tires and wheels is that even if a Hunter 9700 can balance them by the time you drive 250 miles things are out of whack again due to the tire changing under the stress load.......eventually it may stop changing but by then you have balanced them a several dozen times and the tire is worn out.
It's all about total cost of ownership...not purchase price!
People just don't realize how soft those $150-$250 wheels are compared to oem which must last at least thru the 60k warranty vs 90 days or a year.
A $150-$250 tire may not last long but it will sure keep it's balance longer.
Pretty foolish to spend the money on a Hunter 9700 optimization on a cheap tire on a cheap wheel you will be back every month dropping another $100 because if you get them perfect you then get sensitive to the future non perfection. Better to start with Michelin in the first place!
It's all about total cost of ownership...not purchase price!
People just don't realize how soft those $150-$250 wheels are compared to oem which must last at least thru the 60k warranty vs 90 days or a year.
A $150-$250 tire may not last long but it will sure keep it's balance longer.
Pretty foolish to spend the money on a Hunter 9700 optimization on a cheap tire on a cheap wheel you will be back every month dropping another $100 because if you get them perfect you then get sensitive to the future non perfection. Better to start with Michelin in the first place!
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AZhitman
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Well, I guess I'll be in good shape then with 99 OEM alloys and $600 Yoko's (soon to be swapped out for $680 set of Michelins).
p.s. The guy running the 9700 for me the day i went in makes far more $$$ than me. He drives a C5 and his wife drives a 99 Z3... But he's the GM for that store, so.. I'd NEVER settle for the pimply-faced kid busting MY tires.
p.s. The guy running the 9700 for me the day i went in makes far more $$$ than me. He drives a C5 and his wife drives a 99 Z3... But he's the GM for that store, so.. I'd NEVER settle for the pimply-faced kid busting MY tires.
If you lived on or near the West Coast and bought your rubber at Les Schwab, for road force balancing on the hunter we charge about $25 per tire at time of tire purchase. ANY time you come back, and for whatever reason, rebalance is absolutely free of charge. This negates, somewhat, the need for concern about total cost of ownership. If this means spending an hour and a half match balancing your tires on the Hunter 9700, then so be it. It's still free. IMO, charging a customer to redo the job we failed at in the first place is criminal. Les Schwab is customer service oriented. As the slogan goes: "our business is earning your trust". I think we do a good job.
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Q45tech
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The problem is people hate to pay $60 for a tire much less $25 EACH 4 times a year to get them radial force balanced properly!Now that many 17-18" tires are $250-$300 each [20" will be $450 each] the $100 each maintenance sounds more economical.
People expect everything except when they are charged money for it!
When you add tires, brakes, annual/quarterly fluid changes on performance cars these 3 items can easily exceed $2,000 per year BEFORE ANYTHING ELSE BREAKS.
PEP BOYS 4 tires for $99 mounted - scares me to death
People expect everything except when they are charged money for it!
When you add tires, brakes, annual/quarterly fluid changes on performance cars these 3 items can easily exceed $2,000 per year BEFORE ANYTHING ELSE BREAKS.
PEP BOYS 4 tires for $99 mounted - scares me to death
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EZcheese15
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Q45tech wrote:PEP BOYS 4 tires for $99 mounted - scares me to death
Scares me too!! I just spent $750 to get new tires mounted and balanced about 2 months ago. And people ask me why I spent so much money....
The way I see it, I'll never have to get my tires balanced again until they wear out, which might only be 15-20k, but atleast the tires will wear evenly, have excellent traction, and not vibrate.
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Q45tech
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I don't know what kind of tires you are running but I can assure even the best will be more than 7 grams [at wheel edge] out 15/26= 0.57 factor x 7= 4 grams at tread surface just due to tread wear in 3,750 miles.
The most expensive Michelins made still get out of balance just lesser amounts.
Radial force balancing just sets the tire/wheel combo at minimum when new.........things change due to stresses on wheel. You usually don't have to rerotate the tire on wheel at every rebalance but you still have to check it for positioning improvement at least after the initial break in.
When the weight amount increases or decreases you have to find out WHY .......is it the tire or the wheel [especially on very soft cast aftermarket units].
Of course I am professing what is required for an as new ride.
Do a test after a balance clip an extra 7 gram weight on temporarily can you feel the imbalance sure you can!
The most expensive Michelins made still get out of balance just lesser amounts.
Radial force balancing just sets the tire/wheel combo at minimum when new.........things change due to stresses on wheel. You usually don't have to rerotate the tire on wheel at every rebalance but you still have to check it for positioning improvement at least after the initial break in.
When the weight amount increases or decreases you have to find out WHY .......is it the tire or the wheel [especially on very soft cast aftermarket units].
Of course I am professing what is required for an as new ride.
Do a test after a balance clip an extra 7 gram weight on temporarily can you feel the imbalance sure you can!
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EZcheese15
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Q45tech wrote:I don't know what kind of tires you are running but I can assure even the best will be more than 7 grams [at wheel edge] out 15/26= 0.57 factor x 7= 4 grams at tread surface just due to tread wear in 3,750 miles.
The most expensive Michelins made still get out of balance just lesser amounts.
Radial force balancing just sets the tire/wheel combo at minimum when new.........things change due to stresses on wheel. You usually don't have to rerotate the tire on wheel at every rebalance but you still have to check it for positioning improvement at least after the initial break in.
When the weight amount increases or decreases you have to find out WHY .......is it the tire or the wheel [especially on very soft cast aftermarket units].
Of course I am professing what is required for an as new ride.
Do a test after a balance clip an extra 7 gram weight on temporarily can you feel the imbalance sure you can!
I'm running Bridegstone S03's, 215/45/17's on stock rims. I admittingly didn't have them radial force balanced. I was simply referring to the fact that if you spend good money on some good tires, they are better and easier to balance than cheap tires. And my tires will go out of balance, but not as bad as cheap tires. I won't be complaining if I have a slight vibration after 10k, because frankly I don't care. I don't drive a luxery car
However, if I were to have some cheap, hard, tires, that claim to last 50k miles....then I would have to get them rebalanced many times throughout their life. With my current tires, one balance should be good for the life of the tires (well, decent, not excellent or anything).
Anyway Dennis, I know what you mean with all that you said, it's just I'm not very picky at all when it comes to vibration...I mean, I get more vibration from wheelspin and bumps on racetracks to worry about
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szh
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Do you all have a SF Bay Area store? I do not have a phone book handy ...SmithSR wrote:If you lived on or near the West Coast and bought your rubber at Les Schwab, for road force balancing on the hunter we charge about $25 per tire at time of tire purchase. ANY time you come back, and for whatever reason, rebalance is absolutely free of charge. This negates, somewhat, the need for concern about total cost of ownership. If this means spending an hour and a half match balancing your tires on the Hunter 9700, then so be it. It's still free. IMO, charging a customer to redo the job we failed at in the first place is criminal. Les Schwab is customer service oriented. As the slogan goes: "our business is earning your trust". I think we do a good job.
Z
there is either one there now or plans are in the works. i vaguely remember hearing some info about a SF store, but i am not certain. the lower area of Cali is pretty much the only market we haven't heavily saturated on the west coast. you can call the main office in oregon and ask what the status of that store is. 541.447.4136. there are several stores in Cali, but most are northern/central so far. BTW, for those of you that are drug free, it's a great place to work with excellent pay, full benefits, excellent retirement program, good discount, and a chance for any employee to move up into management and bring home six figures annually.