new tires unbalanced when cold?
 

A few weeks ago I had installed Sumitomo HTR Z3s (205/50R 17, 255/40R 17) on RUF wheels (964 offset with spacers).

I have noticed a steering wheel vibration between 60-70mph for about the first 10 minutes of driving and then it goes away. My guess is that the tires warming up puts them back into balance. Wondering if I should have front wheels rebalanced or just live with it. If re-balance, do all 4 or just front?

Last time I had a balance problem after getting new tires, I took them back to the installer, who refused to re-balance them without charge, claiming that it was done right the first time and that I must have "bad" tires. I then went to another place (local Audi dealer!) that balanced them perfectly.

your out-of-balance problem is commonly called 'flat spots' Bill K

sometimes caused by prolonged sitting , mine does the same thing after a little moving on the road all is fine....no uneven tire wear on my cars tires either...if yours is the same i would not worry about it . jm2c, ben

3 questions:
1. Can new tires have flat spots?
2. The problem occurs even if I have driven the car the previous day or earlier in the same day, as long as the tires have cooled down. How long does it have to "sit" for a flat spot to develop?
3. Would re-balancing help with flat spots?

If it is flat spots re-balancing will not help. Flat spots occur when the weight of the car presses the tires against the ground. I imagine some tires are more susceptible to this than others...but my experience with this process usually occurred after several days of sitting. Your tires are high performance tires and I would assume softer tires, this might explain a shorter time frame for flat spots. But I would have the balance checked if they were my tires.

i have a set of kumos that have done this since day one. makes me say i will not use kuhmo again.

I had those tires on a BMW E39 528i and they did the same thing. Flat spot that is.

I notice this on some occasions, if I have been parked for several days, but it goes away in about 10 minutes when the tires warm up.

Has to do with the nylon cap ply. Tires that have no nylon generally don't do this. Nylon "takes a set" when cool, which causes a temporary flat spot that goes away once the tire starts to warm up. Back the old days (bias ply tires), almost all tires did this. These days it's only performance tires. Nylon cap plies are used in performance tires because nylon tends to contract when it gets hot, which tends to make the tires less subject to growth from centrifugal forces at very high speeds.

I have 17 inch Sumitomo Z IIIs on couple of e36 BMWs. They offer a comfortable ride despite the plus 2" sizing, decent performance and wear. They are relatively inexpensive. But, they do flatspot.
Can't have everything, i guess.

I have Kumho ASX on 3 vehicles and find them quite good in most conditions.

We've run several cars that do this. All with meduim to high performance Toyos. My newly acuired 911 does this as well. It's a mile and a half from the driveway to the highway. That plus a mile or two on the highway and they always smooth right out. I just use it as a reminder of the joys of bias plys from my youth. :) Nothing quite like bucking down the road in a CJ-5 on some cold bias ply "Q" Buckshots.

-J

My Michelins A/S's do this when it is colder outside as well.

After a few minutes of driving, they smooth out!

GL!


Rod

With tires that new,..I'd try to return them, should you feel they are flatted.....if the balance is good, WTF?

I know my car (89) is [seemingly] sensitive to properly balanced air pressures...

Just MO.

BEST!

Doyle

Any tire that is in the category that I would call, "Good for sports cars" will get a temporary flatspot after sitting for a bit. Good sporty tires have soft rubber. That makes them more compliant. If it sits for an hour it will have a little bit of a flatspot. If it sits for a day + it will get more of one.
The colder it is the more it will do this. The more sensitive you are to what the car is actually doing the more you will notice it with harder tires and with less precise suspensions. When you get to frozen winter temperatures ALL TIRES do this. If you didn't notice it in winter then it is probably because the the frozen road is covered by uneven patches of ice.

Just drive the tires to get them heated up and it goes away.

You have a car where you are intimately aware of the engine warm up period so you should be aware of the tire warm up period. If you can't deal with a few minutes of a tire warming up then get a nice rock hard, non sporty tire like you would use on a Prius or get a car with a mushy soft suspension that insulates you from what is happening at the tire's contact patch.

+1
the reviews for the tires that i put on my volvo said that they "flat spot" over night and are rough for the first 5-10 minutes of driving. sounds like you have the same issue.

The eagle gts that are on my car flat spot also. These tires came on the car when I bought it.
Dean

I run Kuhmo's on just about everything I own. Yes they will flat spot overnight, especially if its hot the day before when I've driven the car. Gone within a mile in the morning. Price you pay for sticky inexpensive tires. They get no complaints from me.

Found this interesting info on flat spots :

Temporary Flat Spots
Temporary flat spots are simply rubber compression and they go away as soon as the rubber warm and re-rounds. These are always either 1st or 2nd harmonic flat spots. It is crucial to remember that all permanent flat spots begin with a temporary flat spot. The only difference is how long the vehicle stays parked. Harmonics are measured from 1 to 10 with ten being the least case scenario. A first harmonic flat spot ( 1 ) means that for every rotation of the tire, at any speed, the flat spot is felt. As such, you would feel this going 22 mph or 122 mph.

Permanent Flat Spots
A high harmonic flat spot, 6 or above, is often not recognized as a flat spot but is often confused with a mechanical problem. This is best explained as a particular speed where the problem manifest itself. An example would be a car that has a shimmy or vibration from 66 to 70 mph but none above or below that speed range. This is almost always a high harmonic permanent flat spot.

TireCradles

You know, a couple weeks ago I would have told you it's a temporary flat spot because that's exactly what my Toyo Proxes TR1's were doing for months and that's what I thought the problem was. But recently, prior to taking a long trip, I took the car in to have the problem looked at, and the tire shop found that one tire had been balanced with an abnormally large amount of weight. So they took that tire off and rotated it 180 degrees on the wheel and rebalanced (this time it took a considerably smaller amount of weight). Presto - problem solved! It might be worth your while to have an experienced pro take a look at your tires even though the problem is temporary.