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New Tires Today!


halfrican

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Hello All,

Got some new tires for my 2001 STS today, and was curious about the end results. The dealer I went to was very knowledgable and helpful about my choices and preferences. He recommended a tire based on my priorities and gave me what I felt to be a very fare price. I'm not going to get into the brand name/model of the tire debate as I know it will extend this tread longer than necessary, and it's not really the issue I'm concerned about.

After the dealer finished the install and assured me that the balance was "right on" using the Hunter 9700 road force balancer. I drove home on the quietest most vibratition free trip I have ever had in my STS!

Now to the issue I concerned with, after I got home I checked the tire pressure and found that it was very high (near 40psi) at each tire, while the door sticker on my car specifically calls for 30psi cold. I let the tires cool and still found the pressure at almost 38psi. Should I lower the pressure to 30psi as called for on the door, or will this require that the tires be re-balanced? If I leave it at the higher pressure won't I be sacrificing ride quality and handling?

Thanks,

Half

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The tire pressure number on the door is the minimum.

The maximum pressure number is molded into the tire side wall.

Somewhere between these two numbers will be the tire pressure that provides the ride comfort or handling characteristic you prefer.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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If you like the ride quality as is, I'd leave it. In general, the higher pressure you run, the better your fuel economy will be. You can lower the pressures, and gain some ride quality, but lose some fuel economy. Treadwear is also affected by tire pressure. Try to adjust the pressures so the wear across the tire is even. You can see this, in a general sense, by rolling onto a dusty driveway or garage floor. I keep my tire pressures so the outer 1/2 inch of the tread stays untouched. In my experience, if you try to get the pressure so the ENTIRE width of the tread touches the road, the outer edges will wear prematurely.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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If you like the ride quality as is, I'd leave it. In general, the higher pressure you run, the better your fuel economy will be. You can lower the pressures, and gain some ride quality, but lose some fuel economy. Treadwear is also affected by tire pressure. Try to adjust the pressures so the wear across the tire is even. You can see this, in a general sense, by rolling onto a dusty driveway or garage floor. I keep my tire pressures so the outer 1/2 inch of the tread stays untouched. In my experience, if you try to get the pressure so the ENTIRE width of the tread touches the road, the outer edges will wear prematurely.

Well said Jason! Those are the exact guidlines I use. ;)

My feelings/findings are a mix of yours and JimD's. I usually end up running about 2 lbs under the max. on the tire markings, and have good luck with wear and ride comfort. :)

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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I have found with any tire It's trial & error to find a tire pressure that the car rides best.Too much air pressure it rides hard over small bumps etc. I like a smooth ride so on my car I run them at 30 psi cold when you drive the will go up a couple pounds Just let some air out in the morning or add air while the tires are cold and find a pressure that you like

Good Luck

Jim

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I used to run my Michelin XW4's at 35 but when I put Symmetry's on last year 35 was too harsh. They are now at 30 and the ride is pleasant. My preferance is comfort.

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I am an absolute nut (idiot?) about tire pressures—I check mine at least once a month with a digital gauge that reads to 0.5 pounds…I’ll spend 30 minutes fiddling with the tires to get the pressure exactly the same side-to-side…

I always try to check them early in the morning, before the sun has had a chance to heat up one side…my experience is that every 10 degrees F adds about 1 pound.

Also, it seems every brand new set of tires feels like riding on air. My un-scientific theory is that you are riding on the little “knobbies” (tiny spikes from the tire mold) for the first few hundred miles—so you are quite literally “riding on air.” My guess is that after awhile 40 psi may feel too harsh, particularly on city streets. I have found that about 2 to 4 psi more in the fronts of FWD cars (60% of the weight on the front) seems to improve the handling… as stated earlier, door sticker is biased towards a comfortable ride, with acceptable tire wear and handling. Your mileage may vary… B)

Good luck with your new tires… I’m jealous that I can’t seem to find a dealer with a road force balancer in my area...

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First full day with my new tires, noticed some shimmy/vibration in the dreaded 68 to 76 range, took vehicle back to dealer where he tried to rebalance and found one tire with a lateral runout of almost 24. He replaced tire and re-checked the balance finding every tire to be well within the Cadillac spec of less than 14.

Service writer road tested with me and still found noticeable shimmy in steering wheel about 67 and up and decided to make them replace the two front tires even though the Hunter said they were in spec. Afterwhich the ride is "almost" perfect! I still notice a very slight vibration/shimmy in the "dreaded zone" but other than that ride and handling are very good. I did have the dealer lower pressures on the tires to 30psi and find that overall I like the ride a little better (Alaskan highways are very similar to country dirt roads in the rest of the world).

Dealer still doesn't think the shimmy/vibration is acceptable, and has offered to order some Michelin's even though he isn't a dealer. Should I accept his offer and take a chance that the ride doesn't improve? I am sure it won't be possible for him to just pull additional tires off the rack if he finds one out of spec.

My thought is that I am so used to the vibration that I am ultra sensitive to it and may learn to live with it, or not.

Thanks again in advance.

Half

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Dealer still doesn't think the shimmy/vibration is acceptable, and has offered to order some Michelin's even though he isn't a dealer. Should I accept his offer and take a chance that the ride doesn't improve? I am sure it won't be possible for him to just pull additional tires off the rack if he finds one out of spec.

Two thoughts:

1) If you have a dealer/shop who is willing to work with you to get it right, I wouldn't say no to that. It's rare to get someone to even recognize problems these days...if you have one who seems to have an interest in getting the job done to HIS satisfaction, which at least matches yours, I'd let him (given it's not a big inconvenience to you).

2) If you can get a set of Michelins for a lesser price than retail (like it sounds like what's going to happen), again, I wouldn't say no to that. I know you didn't want to bring the tire brand war alive again, but I think it's beneficial to everyone for folks to relay their experiences with various brands, both good and bad. What brand are the new tires that you had installed? What model Michelins will he order? More than one person here has said a Michelin tire has fixed a vibration problem, severe or otherwise. You may be another person like that after it's all said and done.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Dealer still doesn't think the shimmy/vibration is acceptable, and has offered to order some Michelin's even though he isn't a dealer.  Should I accept his offer and take a chance that the ride doesn't improve?  I am sure it won't be possible for him to just pull additional tires off the rack if he finds one out of spec.

Two thoughts:

1) If you have a dealer/shop who is willing to work with you to get it right, I wouldn't say no to that. It's rare to get someone to even recognize problems these days...if you have one who seems to have an interest in getting the job done to HIS satisfaction, which at least matches yours, I'd let him (given it's not a big inconvenience to you).

2) If you can get a set of Michelins for a lesser price than retail (like it sounds like what's going to happen), again, I wouldn't say no to that. I know you didn't want to bring the tire brand war alive again, but I think it's beneficial to everyone for folks to relay their experiences with various brands, both good and bad. What brand are the new tires that you had installed? What model Michelins will he order? More than one person here has said a Michelin tire has fixed a vibration problem, severe or otherwise. You may be another person like that after it's all said and done.

Jadcock,

I agree, once the issue is resolved and I have proof that the Michelin tires are truly superior to the current brand that I am using, it would be glad to share my brand experience as a benefit to the other members.

However, at this point, it seems that that the "brand x" dealer's willingness to support my concern and accept the fact hat his product may be inferior to the competition is still the true value.

Going to talk to dealer today will get back with the quote for the "upgrade".

Half

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Check out the Michelin web site for the best tire for your car michelin offers many tires some are good for handling others smooth quiet ride If I recall each number they rate the tires for in each catogory is 10% Say a tire that is rated an 7 for handling vice one that is 9 the 9 would handle 20% better than the 7 rated tire

Worth a look Check each catagory to find a tire that suits your needs

Good Luck

Jim

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Check out the Michelin web site for the best tire for your car michelin offers many tires some are good for handling others smooth quiet ride If I recall each number they rate the tires for in each catogory is 10% Say a tire that is rated an 7 for handling vice one that is 9 the 9 would handle 20% better than the 7 rated tire

Worth a look Check each catagory to find a tire that suits your needs

Good Luck

Jim

Tire shop getting the Michelin Energy MXV4 Plus 235/55/17 tires in this afternoon, they are swapping them out in the morning, will update then.

Half

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Those are EXPENSIVE tires! About $150 ea. depending on size and tire shop I believe. I hope you like them. Financially, it looks like you're getting a great deal.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Should I lower the pressure to 30psi as called for on the door, or will this require that the tires be re-balanced? If I leave it at the higher pressure won't I be sacrificing ride quality and handling?

I always used about 85% MAX pressure for a rough guideline

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Those are EXPENSIVE tires! About $150 ea. depending on size and tire shop I believe. I hope you like them. Financially, it looks like you're getting a great deal.

Actually I am paying the difference between the cost of the original tires and the Michelins, but considering the effort they have made to make things right, and the fact that they have the Hunter 9700, I think it's fair that I pay that much. They are not charging me for the re-install, nor are the deducting any value on the original tires that I have already drove some 200 miles on since I got them. In all honesty, I love the original tires they sold me (sans the vibration/shimmy) they are quiet, good handling tires.

More info in the a.m.

Half

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Back from the tire shop, and a spirited test drive involving winding hill-laiden back roads and some highway cruising. So far I am very happy with the Michelin tire, vibration/shimmy is all but gone (still slightly there, but I am so hyper-sensitive to it now I am going to try to live with it).

Original tires that I tried were the Cooper LifeLiner SLE's, they really weren't a bad tire and I think that they had about 85 to 90 percent of the ride quality of the Michelin's but the extra $200.00 for set made the Michelin's a worthwhile upgrade IMHO.

Once again, I can honestly say that Dean and Justin at Diversified Tire in Wasilla Alaska are true professionals in their industry. I wish all of my experiences with service for my car could be near this quality.

Started out with 30psi all around, and will experiment with higher pressures over the next few weeks. My STS is equipped with the Tire Pressure Monitors so I can't go as high as some have described without triggering a DIC code, but I will experiment none the less.

Thanks again, you guys are the best of best!

Half

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I am an absolute nut (idiot?) about tire pressures—I check mine at least once a month with a digital gauge that reads to 0.5 pounds…I’ll spend 30 minutes fiddling with the tires to get the pressure exactly the same side-to-side…

Felix Unger! Where have you been hiding?!?

Sorry, I just couldn't help myself. :D:D:D

Regards,

Warren

P.S. If they ain't too flat on the bottom, and don't yield to my thumb, I'm simply not worried. :P

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There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises

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Hi halfrican

I have the same set and size of michelins on a dts they are nice tires I run mine at 30psi cold after driving they go up a couple pounds I have the tire monitoring sys to check the tire pressures so it's a toy that I play with all the time. I air the tires when I have a split between tire pressures I try to keep the equal but it's a pain in the a-- most of the time I usually air them at the gas station overfill around 36 psi then after the car sits overningt then in the morning I let out the needed air until I'm at 30psi. these tires ride good at 30psi but if you kick up the pressure to 40psi they ride very hard same as any tire One time my wife took the car in for an alignment they aired the tires to 40psi and on the freeway I had to pull over in a rest stop and let some air out you felt every bump crack etc. in the road..At first I thought what the F is wrong this don't feel rite.checked the tire press sys and bingo 43psi I got out let some air out and all was well..

Good Luck

Jim

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Halfrican, thanks for sharing your experiences. Like you, I wish all tire shops, or even ANY auto shop of any type, would work with the customer the way it sounds like they worked with you. Most of all, I'm glad your vibration is fixed to your satisfaction.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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  • 2 weeks later...

Wow!

Still had some vibration even with the Michelin's and was just about ready to concede that it was a "feature" of the STS.... But, then I decided to double check some of the other issues related to the vibration.

1) New Tires (road force balanced)

2) New Rotors and Pads (all around)

3) New Sway Bar Busings (front and rear)

4) New Sway Bar Links (front and rear)

5) Tire Pressure (set at 30 psi all around)

6) Alignment (4 wheel)

Finally, I decided to purchase a Micrometer Torque Wrench and double check my lug nuts. Tire shop insisited that they torqued them to spec, but I found the nuts to be inconsistently difficult to unbolt. Re-torqued all of them using the star technique in the manual and set them to 100 lb/ft using my new toy, and all I can say is WOW, the vibration decreased another 75% at least. It's still there but it is getting to the point that I only notice it when I slow to below 55 and it smooths out a little more (kinda like not noticing a noise in the background until it stops).

I am now convinced that the ride quality is about as good as it's going to get!

I realize that lug nut torque is a important issue, but had no idea how big of an effect it could make on the STS.

Hope this helps others.

Half

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