Some of you may have read my problems with a vibration I can't seem to get rid of. I've had the roadforce balance done at my local discount tire where I purchased the tires. Because the tires are slightly cupping, they are now recommending that we switch the tires from side to side. Meaning taking the tire from the left side and putting it on the right side. I have the P-Zero's and they claim these are a multi directional tires so this okay to do. Is this okay to do? Would you guys do this? My fronts have 15k miles on them and I would guess i can get another 5k out them. My rears only have 4k miles, I got 11k miles on my first set of rears.

Is this a smart idea or do they not know what they're talking about?

 

Since the development of steel belted radials, it has become less recommended to swap tires from one side to the other. Obviously, when you do that, the tires will now be going in the opposite direction that they were going earlier. These belts migrate slightly within the tires and set themselves based upon where they are (front,--steering tires) and how they were rotating. It has long believed that you can cause a problem by swapping tires left to right, resulting in the steel belts attempting to reset themselves based upon a new direction of rotation.

With a high performance automobile, I would not do this. What you should do it get to the bottom of the cupping problem (still awaiting photos) is by doing a proper alignment check on all 4 corners. THEN, and only then, put on 4 new tires that have been Road Force balanced.

 

I suspect they are not talking about rotating (just moving one wheel tire from each side to the other side). Instead they are talking about taking the tire off the rim and mounting it inside-out on the opposite rim so the tire will be going in the same direction but if the cupped area was on the outside before it will be on the inside now.

Its a common practice to do this with track tires to extend their life. If the tread is directional, its done when they are worn pretty far down, if they are not directional it can be done any time.

My guess is that this will help a bit and you might get a few more miles out of these tires assuming your alignment is now correct. But if it doesn't work (you continue to feel the vibration from the cupping) you'll have wasted the money and still end up getting a new set of tires.

 

I'd be sure alignment correct. I read of one Porsche owner who had a similar experience and went around and around having tires checked, re-balanced, alignment checked -- he was assured it was fine -- and still the symptoms persisted.

Finally in desperation he took car to another highly recommended shop and found out the alignment was not correct. The first place -- official Porsche dealership IIRC -- was just stringing him along.

Moving tires from side to side -- as long as direction or rotation kept the same is ok. However, the tires have to be demounted, remounted, and the wheels/tires rebalanced. High performance tires do not necessarily like this. Also, it puts the wheels at higher risk of being marred by the tire equipment.

The moving of the tires from side to side is just some last resort attempt to make the symptom go away.

I think you'd better find another tire shop -- dealer perhaps -- with Hunter tire balancing system and have all tires re-balanced. Ask tech to check all wheels for signs of excessive run out or any signs of damage.

Also, have car treated to proper alignment. While on alignment rack ask tech to check for any signs of steering/suspension damage, excessive wear or tear, and for any signs of excessive adjustment to bring alignment into to spec. If this found car could have been bent in accident. Also, have shocks checked for any signs of needing replacement.

Another possibility is to find someone that will loan you a set of front tires/wheels for a test ride to see of a change in wheels/tires makes the symptom go away.

Oh, I would add that I have had poor luck with independent tire shops. They do not know how to properly lift a Porsche and I've stopped the tech from lifting the car impoperly. One guy wanted to raise rear of car placing jack under engine sump. Another was going to jack front of car by placing jack under front end somewhere. Another place used hammer on wheel weights.

Now all my tire work done at Porsche dealer service department. Indy tire stores suck is my experience.

Sincerely,

Macster.

 

There can't be much life left in your front tires at 15K. Tires could be out-of-round too, but the dynamic roadforce should be able to find this.

 

u can flip flop side to side making inner the outer, but make sure they are not inner/outer tires before then.. ;-)

 

If tires are cupping, then I suspect there's a suspension problem. Worn balljoint or tie rod end. Possibly shocks. Tires just don't do cup on their own. As suggested, I recommend having a shop take a look at alignment and front end components.

 

Thanks for the responses, I did try to take a picture but the cupping hardly shows up in the photo. Just to be clear Discount tire is recommending I switch them from side to side not taking the wheel off and then remounting it. They claim the tire would then be going the other way and in effect would be wearing the orignal cupping down. I'd love to take it to my dealer but they just sub it out to another wheel/tire company.

I'm taking the car in for a oil change in the next few weeks, i'll have them check the alignment specs as well as the suspension.

 

Never underestimate the value of skilled tire mounter. Discount tire places MIGHT have one but.... My point would be that the tire shop is the issue.

Hunter Road force balancing machines are only as good as the tech using them (this from my own experience).

Assuming that you've alread tried the Porsche dealer - What you need is a race shop. Take the wheels off two and a time and ship them UPS if you don't have a race shop within driving distance.

If you haven't tried the dealer then go in and tell them to knock all the weights off and start from scratch. Or, if you have a race shop near by just go straight to the pros.

 

I've made an appointment with local dealer to look at this issue. The temperature has dropped into the 40's and 50's and the problem has gotten alot worse? Does that give any more clues as what this could be? Do balance issues come out more in teh cold?

 

Did you adjust your tire pressures, with the drop in air temp? You are now low on air too.

 

Cars generally get noiser in colder weather. Parts fit a bit more snugly and bushings and other softer items get firmer in colder weather. Tires of course get a bit stiffer. If there is any out of balance or out of roundness or any issue like this at all the symptoms almost always will get worse as the ambient temperature drops.

As another poster rightly pointed out tire pressures need to be checked. A drop in temperature will cause cold tire inflation pressure to drop. Roughly a 10F drop in air temperature results in a 1psi drop in cold tire inflation pressures.

Be sure tires are not overinflated. My 02 Boxster has several times exhibited a vibration at higher speeds (freeway speeds or thereabouts) and upon checking the front tire pressures -- with tires cold -- I found they were high by several psi.

I doubt this is the cause of your symptoms but be aware the high performance tires can develop flat spots. What I've found is this is more common in milder temperatures.

On a mild day the tire can get hot enough to get well, nice and warm. Then the car's parked for the night. Nighttime temps drop and the soft tires as they cool take a "set".

Upon driving the car again the car can exhibit a vague vibration that is the tires. This vibration won't last long as the car is driven cause the tires heat up of course and lose the set they acquired over night.

Warmer temperatures do not see this happening cause tires don't cool down enough to take as much of a set.

And much colder temperatures do not see this happening cause the tires don't get hot enough when the car being driven to upon cool down take a set.

It is the milder spring and fall days with their milder temperatures that I notice this happening. But even so the vibration is mild and short lived. Just a mile or two of city driving is enough to find the tires smoothing right out.

Sincerely,

Macster.