dug-mac

Let me preface this by saying that I don't know a lot about cars. Here's the situation. I just had my 4 Yokohama Avid V4S's mounted and balanced. The car tracks true, with no fading to either side. I should note that the car had a 4 wheel alignment 8,000 miles ago, so I didn't feel the need to have another even though I was putting 4 new tires on. Again, the car tracks very true - straight as an arrow. However, I notice that the ride is somehow coarser than before and that the wheel shimmies somewhat when I apply the brakes, particularly so when decelerating from highway speeds. I suspect this means that one or more of the tires isn't completely balanced. I've had cars where the tires were obviously mis-balanced - the wheel would shimmy at any speed even without using the brakes. I don't really notice the shimmy (maybe it's there, maybe it isn't - hard to tell) in the wheel without applying the brakes. When the brakes are applied, though, the shimmy is fairly obvious particularly if you apply them with moderate pressure from, say, 80 mph. Does this sound like a mis-balanced tire or tires? Thanks for any help in diagnosing this one................. Doug

JPTL-S

Sounds like you might have warped rotors

dug-mac

I suppose that could be, but they weren't warped before they put on the new tires. I should note that these tires are brand new and I've only put 100 miles on them. I don't know if that would make any difference or if they might "settle down" with time...

JPTL-S

I actually have a set of Yoko V4S's on my wifes car and I did notice that they were susceptible to flat spotting, but that clears itself once the car has been driven for a few minutes. But, that would not really explain the vibration while braking. Can anyone else lend their expert opinion to dug-mac?

03CoupeV6

What he is describing is the classic warped rotors effect. Perhaps the lug nuts were over tightened?

dug-mac

Thanks for your response. How would over tightening the lug nuts cause this? As I said, I don't know too much about cars...

03CoupeV6

Over-tightening love nuts will cause warped rotors from everything I've heard on this board in the past.

EDIT: Whoops, you know I meant lug nuts, but that mistake was too funny to correct and not mention.

dug-mac

Yeah, over tightening love nuts will certainly cause warpage ;-). Maybe I'll let the car cool down a bit and see where I'm at. Is it possible for that warpage to be worse while driving at highway speeds and then appear to be better once the car has cooled?

03CoupeV6

When you have warped rotors it will be more pronounced when slowing from highway speeds than around town, independent of car or ambient temperature. Stopping from 40mph probably won't cause much vibration at all, but stopping from 60+ will cause a lot of vibration.

dug-mac

Yeah that makes sense and seems to be what I'm getting. Is it possible for that apparent warpage to disappear when the car cools down? I was applying the brakes a lot from about 80 mph because I thought I had a problem with the tires. Now it seems that wasn't a good test of wheel balance after all. I'm still a little suspicious that the tires might be just slightly off balance, but perhaps I shouldn't expect the high performance Yokos to ride as smoothly as the Grand Touring Michelins?

dug-mac

Let me try to say it another way. Isn't it possible for the rotors to have heated up from my consistent high speed braking, and isn't it possible for the "warpage" to recede slightly when the rotors cool?

Lawaia

Make sure the hubs are clean and free of debris. Take the tires off and check the wheel mounting surface as well. Torque lugs to 80 ft/lbs. Also, check your tire pressure.

JetJock

I bought new tires a few months ago and had a vibration at 80mph+. I had the tires rebalanced twice but they could never get the vibration to go away. Then I found a dealer that had the Hunter Roadforce Machine...problem solved! I highly recommend anyone with good tires get them balanced on a Roadforce Machine. There is nothing around like it.

fsttyms1

If the shaking only happens while braking its your rotors. Its very possible that when the place that installed them they over tightened the lugs causing the slight warpage. the more times you do highspeed (heat inducing) braking the more likely you are to warp them. (especially on the TL which is known to have poor quality brakes that are prone to warping)

dug-mac

Thanks everyone for helping me out with this. I'm coming to the conclusion that the tires balance is fine. Sometimes you can be too close to something to see it clearly. Of course the vibration in the wheel while braking was the rotors - it is so easy to see that now. My only saving grace is that I told everyone I didn't know much about cars... I think what I'm experiencing with the tires is their more aggressive tread pattern. I can actually "feel" them bite the road, whereas the Michelins were just kind of vague. This bite gives them a little coarser ride, I think, on perfectly smooth surfaces compared with the Michelins, which just seem to float like being on a cloud. On bumpy surfaces the Yokohamas are far more compliant than the Michelins, which suffer from too hard a compound tread (I think). I still have a couple of questions though:

1. Does any of this make sense?
2. Since an Acura dealer mounted and balanced the tires can I assume they have that new Hunter balancing machine?

Thank again, Doug

YoungGun

This all makes sense to a car that vibrates when braking... But what about when it vibrates or bounces when going a certain speed... say 45mph and 80 mph... Could it be the air pressures, balancing??? Any sugestions