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My 2001 STS has been having tire vibrations and not always under the same conditions. Different speeds, uphill, down hill, speeding up and slowing down, but never consistantly. I suspect a broken tire. My Goodyear Eagle RS tires are at 50%, but I figured I would replace them to see if that would make a difference before I spent $1500 on struts. I went down to the Goodyear store and got a quote for tires at $315 a tire, plus balancing, etc . . . Then I remembered that someone on the forum here recommended Discount Tires. The closest one is in Albuquerque, 145 miles away. Wednesday I went to their website and ordered tires. I got Pirelli Pzero nero's: All four for $504 delivered to my door. They came today, only 46 hours after I ordered them! I am very impressed by the delivery/service! I went out to my STS this evening to go to a party and found the right front flat. In the morning I will pump it up and take the car to Big O tires to have the new ones put on. I am going to keep the old Goodyears. If I find I still have the vibration, then it is not the tires' fault and I will have the old ones to use later.

Has anyone here used Pirelli pzero nero tires? These are 235/55ZR 17 W98.
 

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Try to find the highest tech. front end and tire shop around. I had a vibration in my 2002 STS, twice back to dealer with no fix. I found a local guy with the latest high tech tire machine, a Hunter GSP9700 I think, it cost about $18,000 so I am told. Anyway, it measures road force, lateral rim runout, radial rim runout, road force, it diagnoses the tire, the rim, and then both as an assembly. The machine also dynamically balances the assemblies, my pressures called for were 31.8,31.6,31.4, and 31.5 no two the same, and then it determines placement on the vehicle for least pull. Mine were placed for Zero pull, I had one tire that failed the runout test, but passed as an assembly. I also found out tires are actually manufactured slightly oval. The end result was a perfect alignment, no pull and no vibration. It took a little time but well worth it. This machine does quite a bit more than I mentioned here and also has a video which quite simplifies the process and prints out the results for your records. I was impressed and I found my permanent tire man. I guess my point is, make sure you eliminate the tires and tire and wheel assemblies before you start looking for trouble where it is not. I was thinking I had additional problems until I totally eliminated the tires or rather discovered the tires as the problem. That machine doesn't lie.
 

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Boombottz said:
Try to find the highest tech. front end and tire shop around. I had a vibration in my 2002 STS, twice back to dealer with no fix. I found a local guy with the latest high tech tire machine, a Hunter GSP9700 I think, it cost about $18,000 so I am told. Anyway, it measures road force, lateral rim runout, radial rim runout, road force, it diagnoses the tire, the rim, and then both as an assembly. The machine also dynamically balances the assemblies, my pressures called for were 31.8,31.6,31.4, and 31.5 no two the same, and then it determines placement on the vehicle for least pull. Mine were placed for Zero pull, I had one tire that failed the runout test, but passed as an assembly. I also found out tires are actually manufactured slightly oval. The end result was a perfect alignment, no pull and no vibration. It took a little time but well worth it. This machine does quite a bit more than I mentioned here and also has a video which quite simplifies the process and prints out the results for your records. I was impressed and I found my permanent tire man. I guess my point is, make sure you eliminate the tires and tire and wheel assemblies before you start looking for trouble where it is not. I was thinking I had additional problems until I totally eliminated the tires or rather discovered the tires as the problem. That machine doesn't lie.
True!

The conventional tire store and employee are not sufficient to handle the newer Cadillac and Corvette tire and wheel balance requirements. If the dealership service writer or shop manager sluffs the job off to a lot jockey you get the same results as if you took the car to Wal-Mart. In this case what you don't know can hurt you.
 

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Absolutely!
Some dealers have 50 techs and only one tire machine. So I wonder if sometimes the job even gets done at all. My tire guy told me I should have had a print out for before and after alignment and or balancing. Also after repeated attempts with no results, some shops could gouge you for additional repairs if you are not wary. The proof was in the pudding for me.

On another note, does anyone know where I can get a lug nut cover for my STS other than the dealer? I think they screw on the lug nut itself.
 

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Boombottz said:
On another note, does anyone know where I can get a lug nut cover for my STS other than the dealer? I think they screw on the lug nut itself.
Only thing I can think of is a salvage yard or ebay. You'll have to buy them as set (I think they come in 5's) at the dealer. I purchased 15 new ones - they really weren't too much money at all.
 

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I replaced the Goodjunk tires on my '01 STS with the same Pirelli Pzero nero's. $556 complete from a local tire shop. They found one slight bent rim during the install. Since I needed a rim repair they did traditional balancing and said bring it back once repaired. After the rim straightening the shop re-balanced on the Hunter roadforce (free of charge) and what a difference. All vibration gone. Some could be attributed to the bent rim but not all. The difference was too great.

Chris
 

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Great. I will probably go to the dealer and buy a set of five. It's always good to have some spares. I thought maybe they could be available at any parts store, but I am finding otherwise. Am I correct that they screw onto the lug nut? I haven't personally removed any from my STS as of yet.
 

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Yes, they screw on to the lug nut. They are pretty flimsy so don't over tighten them, just about 1/8 turn past finger tight.
 

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I bought a set of 10 for $20. GMpartsdirect.com should do it for you. Is there a site that tells where a hunter balancing machine is nearby?
 

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Firewireman said:
I bought a set of 10 for $20. GMpartsdirect.com should do it for you. Is there a site that tells where a hunter balancing machine is nearby?
I am not sure about that Firewireman. I just happened to luck into this local shop with a competent mechanic with high end equipment. There are probably equally good machines out there but they are only as good as the operator. I could give you this guys number and maybe he could direct you to someone near you.

Vince
 

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I bought a set of Kumho ECSTA ASX tires, http://www.tirerack.com/tires/tires.jsp?tireMake=Kumho&tireModel=ECSTA+ASX&vehicleSearch=true&partnum=36VR6EASX&fromCompare1=yes&place=0&speed_rating=PR&speed_rating=QR&speed_rating=SR&speed_rating=TR&speed_rating=UR&speed_rating=HR&speed_rating=VR&speed_rating=ZR&speed_rating=WR&speed_rating=YR&minSpeedRating=H
to replace the old ones on my 99 STS. They single handedly got rid of all the vibration and shimmy when above 60mph. Not only that, they stick to the road like glue and are EXTREMELY responsive. They mounted and balanced with no counter wights on any of them! If you're still vibrating all over the place and about to replace your tires, I'd recommend these! :thumbsup:
 

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Firewireman said:
I bought a set of Kumho ECSTA ASX tires....They mounted and balanced with no counter wights on any of them! If you're still vibrating all over the place and about to replace your tires, I'd recommend these! :thumbsup:
No weights on any of the tires??! What are the odds of 4 tires on the same car not needing balancing? That's very hard to believe. Are they on the inside rim where you can't see them? You must lead a charmed life!
 

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I was just going to ask is it ok to static balance on the inside of the wheel? I just think anyone that puts weights on the outside of an alloy wheel shouldn't be working with tires. And when you call to ask do the people really know what kind of tire machine they have?

I usually go to my local Ford dealer. They're a Tire Rack installer and their service dept has been second to none around here for 100 years. Seriously if there is a service dept at a dealership to trust it's these guys. I wish I could use them for more than tires.
 
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