azkaty

This may be a very complicated question, or very easy for the "gurus"...we have Eagle GT's on our '02 with less than 4,000 miles on them. We had a bad vibration @ 65-68 mph, and decided to replace the original wheels with NEW Tourmalines from Sewell. The vibration had subsided after about 300 miles, but if the car sits for 5 days without driving, we have serious "thump,thump,thump" for about 20 miles, and then gets better. Since my wife is now (I created a monster)looking at buying an SC..I have driven several cars, even with run-flats, and they have LESS vibration, and ride smoother than my SC!!! I am running tire pressure @ 37 lbs, and comparing my car to the ones I am driving, it rides like a TRUCK!! All services have been done, has 53,000 miles, and am starting to wonder if I need struts and shocks, am I over-inflating tires or ??? The other cars that I am driving seem "tighter" and quicker than mine...'02,04..with slightly less mileage...I don't know where to begin to "fix" what may be wrong...or NOT wrong...please give me your advice!!! Bob

Bon

Flat spotting. This happens to all tires to some degree. It has to do with a warm tire cooling down and the portion of the tire that's against the ground is pressed flat. The longer the tire sits like this the worse the flat spot. As you drive the tire warms and flexes and becomes round again, more-or-less but until then: thump, thump, thump. I've seen it so bad that there was separation of the tire plies and the tires were ruined. This was caused by the car being a garage queen and sitting way too much. There are products that you can park on in your garage that are rounded to match you tire shape. You park on them and your tires maintain their round shape. This is extreme but for cars that sit a lot it might be a solution. Flat spotting isn't anything that is specified when a tire manufacturer advertises their tires but you might get some info about this by visiting tire rack. When tires are more susceptible to this problem people tend to complain and mention it in their feedback. It's not really a problem with run flats specifically. I don't know anything about Eagle GT's specifically. Again, I'd check tire rack's reviews and owner feedback to attempt to see what others are saying about your tires. I'm running 245/40R-18 Bridgestone Potenza RE960AS Pole Position non-runflats and I'm very, very please with the ride, handling and tire noise. I run 33 psi.

azkaty

Ron, thank you...these tires would NOT have been my 1st choice...but at only 4,000 miles, hate to replace...just cannot believe that there is anything else wrong with the suspension on this very well cared-for car...thank you! Bob

azkaty

Ron, thank you...these tires would NOT have been my 1st choice...but at only 4,000 miles, hate to replace...just cannot believe that there is anything else wrong with the suspension on this very well cared-for car...thank you! Bob

scdroptop

iTrader: (1)

azkaty-I put Eagles on my infiniti and had similar problems and went back to NTB (last time I ever used them) and got my money back and went and bought some Yokohamas and never looked back. I was told by some snooty tire guys that Eagles are "like truck tires" and are crappy tires in general.

Before I actually got my money back, I had one tire that had a visible "bubble" on the outside and one that wouldn't "seat" right with the rim...all this before I ended up giving up having them balanced and rebalanced.

If this isn't an option for you, you can do what I am doing right now with my 20"s I can't get to settle down---just keep getting them road force balanced, rotate, play with the tire pressure AND ABOVE ALL--drive it more if you can. Even if it's out of the driveway and down the street. I noticed with my 02 and my 05 that I get some flat spots.

Normal flat spots should go away as the tire gets warmed up.

Another tire expert told me that one trick to rid of dead spots is to let all the air out and then air up again. Another told me to try nitrogen.

Unfortunately I don't think there is a "magic bullet" for fixing this. You definitely shouldn't be having that much trouble with the 18"s Tourmalines though. You would expect this on upsize wheels.

See if you can get your money back???

azkaty

SC, you have MUCH more experience than I on sc430"s...these tires came with the car when I purchased...I have read that the suspension on the 430 is very, very sensitive..it just seems wierd that the car seems "heavy" when I now compare with the additional 430's that I've driven..have no problem with replacing these tires...I am sure that Discount tire will work with me...just want to make sure that I am not "missing" another problem...the 430 I drove this afternoon, a 2004 with 42,000 miles with Dunlap run-flats seemes much "lighter" and responsive than mine...better ride, and better feel...am I crazy? Bob

scdroptop

iTrader: (1)

No not at all-you are not crazy. Defintely "felt" that too when I first took delivery two weeks ago of my 2005 PB with oem wheels (light feel) because I was used to my 2002 with 19's on it. When I was test driving even super pristine 2005-2007 cars with super low miles and new tires on them, the RFT's felt smoother than my 19's and now my 20's but still were somewhat rough. I have had extensive conversations with many technicians at the dealer and they say that this is the # 1 complaint about the SC.

Also, you have to remember that the RFT's have a very very hard side wall and Z rated tires. What are your Eagles....V-rated? Also treat pattern makes a difference too.

Not sure on the weight, but perhaps the RFTs are lighter?

I would definitely try to exchange them at DT. They work with me all the time with me and my three cars. I keep them busy. Make sure they are checking the torque on the lugs, air is good too. You'd be surprised. I've asked the manager to get involved a couple of times on the re-balancing. I'll bet they'll let you exchange.

They are open here in Tx on Sundays...you should go tomorrow! GL and keep us posted. Don't wait too much longer though. I think they have a "ride guarantee" but I am not sure how long.

azkaty

SC, I always appreciate your experience and input...am I over doing it at 37 lbs of air? Thinking that the best ride and handling ...so far....were OEM Yokohamas...but do not remember all of the tire info...do you know? Bob

scdroptop

iTrader: (1)

No, not necessarily, but in AZ remember your tires warm up and might get to 40. Like I mentioned, try reducing down a little to 33/34 and see if that helps. I have played up and down with my tires on both my cars with custom wheels forever. You can sometimes find a sweet spot between mfg recommendations and your comfort level.

I am a big Yoko fan...had them on two SC's, both infinitis and several other older japanese luxury and tuner cars I've owned. I think they make a great tire for a good price. Just my two cents though.

Harold57

I agree with all that flat spots do occur the longer you let the car sit. However, not all tires are created equal here, some are worse than others. My Pirelli RF's do pretty well. My Bridgestone R040's before were moderate. There really isn't much you can do to reduce the flat spot issue, other than driving it more often, that I'm aware of.

I'd lower the tire pressure to the 32/33 lbs level (or whatever it states on your door frame). At 37 lbs, the tires start to get a bit harsh and truck like. That pressure will just accentuate the RF stiffness. Hopefully, that will reduce the stiff ride for you.

tromly

Switch to nitrogen, well worth the money. My Lexus dealer charges me $50, but no tire problems. Good Luck

scdroptop

iTrader: (1)

tromly-do you think nitrogen helps with flat spots from sitting and 20's that wobble (even with hub centric rings and proper balance)??? So...you are saying Nitrogen is our new Savior? he he I am about to do it and am questioning if it is worth the money.

azkaty

Finally had the time this afternoon to check the tire pressures: RF38, RR36.5, LF 37.5, LR 36.5. Adjusted all to 34. Car handles and rides 100% better....no more bouncing (jumping feeling) over imperfections in the road, handling feels "light" and responsive rather than "heavy". Can't believe the difference. However, the vibration is still there at 65-68. Tires are Eagle GT 245/45-R-18 96W. I am convinced that there must be a tire with a slipped belt or sidewall problem. These tires were on the car when I purchased about 7 weeks ago...had them rebalanced by DT, still had the vibration, replaced the wheels with Tourmalines from Sewell, mounted at my local Lexus store. Seemed to get a little better after 400 miles, but definitely still there. They have only 3,604 miles since new. At this point, I will go back to DT ( tires have warranty package) and see if we can exchange to...what is your recommendation for Yokohamas (need tire specs) or Bridgestone, or Continentals...have read good reviews on these brands on this site, but need the details. I can't thank you all enough for your advice...was thinking that something was seriously wrong with the car...Thanks again, Bob

Harold57

The 50 to 60 or 60 to 65 mph vibration seems to be a common issue with all the SC430's. I'm not sure just what is the cause. I read about it a lot on the forum and have the issue myself, though it did seem to go away for a while when I got new tires and also later when I had them rebalanced. My best guess would be that the incident speed range must be the resonant frequency of the suspension system, so most likely the solution will ultimately lie there. (I just try to stay above that speed or where necessary, below it.)

azkaty

That's what we have done so far..just stay away from those speeds.

But I am hoping there will be a final solution!