New wheels/tires= Vibration/shaking?? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

986speedster · 02-25-2008, 06:08 PM

I just switched from stock 17"z to 19". There is no issue with clearance or rubbing. The tires were mounted and balanced. I took it out for a quick test run, and past 30 mph, the car vibrates and shutters. Could it be they werent balanced properly, or do you think it could be an alignment issue?

djomlas · 02-25-2008, 07:18 PM

maybe u have directional tires? wheel bolts not torqued properly?

Sammy · 02-25-2008, 07:19 PM

Quote:

Originally Posted by 986speedster

I just switched from stock 17"z to 19". There is no issue with clearance or rubbing. The tires were mounted and balanced. I took it out for a quick test run, and past 30 mph, the car vibrates and shutters. Could it be they werent balanced properly, or do you think it could be an alignment issue?

I think you should take them back to be rebalanced. I put new tires on my old Turbo twists and I had a slight vibration (65mph+) and once I had them rebalanced it went away. The same happened when I went to new wheels and swapped the old tires on the new wheels. I had to take them back for a second balancing (big vibration 40mph+). I think in one case a wheel weight had fallen off and the other was simply a poor balance. No big deal as the place I always go to stands behind their work. Seems dumb that they can't get it right the first time (using the fancy Hunter dynamic balancing equipment) but oh well.

The alignment could possibly be the issue but highly unlikely (can't even think when this would be the case?) especially since it sounds like you didn't have the vibration before the 19's.

Cloudsurfer · 02-25-2008, 07:19 PM

How were they balanced? I would make sure they are balanced on a Hunter Road Force balancer. Wheels that big can be very tricky to get balanced properly, and even a slight imbalance will cause considerably vibration.

Patrick

boxs2000 · 02-25-2008, 07:42 PM

Your vibration and shimmy could be caused by a few things. This is what I would check first before you blame it on bad balancing. Presuming it was properly balanced;

1st check to make sure you are using the proper lug nuts. Jack the car up, remove the lug nuts and look at the tapper on the the ends, if I remember correctly, the o.e. Porsche is a rounded taper, make sure it matches your new rims. Some rims have a strait taper some are rounded depending on the brand and style.

2nd while you have it Jacked up, remove the wheel check to see if the new rims are "hub Centric" What that means is, just like your stock or o.e rims, when you remove the lug nuts the rim fits snugly around the hub of the car.

3rd make sure the direction of the tires are pointing in the way .(directional tires)

I don't think it is an alignment issue, a bad alignment usually causes poor handling and bad/un-even tire wear. I do recommend you get a new alignment since you have new tires and the way the car is going to stand will be different. Its always a good idea to get re aligned when you get new tires.

You did not mention what brand your new rims are. Not to imply that your new wheels are of lower quality, but many after market wheels that are not Porsche or brand specific tend to come in many fits all vehicle configuration which is why they make them that way to be able to mount on many different cars instead of one specific brand.

Lil bastard · 02-25-2008, 07:43 PM

One thing, if any weights were added, with a rim that wide on such a big wheel, you can get into trouble putting all the weight in a single spot. If X amount of weight is called for, it's best to halve it and place one weight on the rimside toward the center of the car and the other toward the outer rim. A Tech may read it needs 6 grams and place a single 6 gram weight in a single spot. This can actually cause an imbalance. The Tech is ignorant of this and is just going by what the readout told him - he added the correct weight, so all must be good. It's a common mistake, especially it it was done at a commercial Tire shop instead of a Race shop. On these cars, personally, I would never take it to a Tire shop. The suspension and handling is just too sensitive and will really magnify an imbalance. The same is true of an alignment. I mean look at the guys working at Firestone and Goodyear, how much confidence can they possibly inspire? They spend 99% of their time mounting tires on Buick SUVs and Chrysler Minivans.

Also, just a note, inverting directional tires will not cause an issue at all with Tire balance. What makes the tires 'directional' is that their tread pattern is designed to channel water away from the car, throwing it to the outside. If you reverse them, you're now directing the water under the opposite tire which can cause big time hydroplaning and loss of control. This is why you want to mount them in the proper direction, nothing more.

Lil bastard · 02-25-2008, 07:48 PM

@Boxs2000 - Excellent points! +1

Benny986 · 02-26-2008, 02:27 AM

great points on the ball vs cone seat lugs, but that probably isn't it. it will still seat properly, its just not good for the wheels and may be dangerous down the line, but it should still center the wheel.

are you using non hubcentric spacers? that will do it.

also, i bet a weight fell off the wheel. some people put tape over their weights to make sure they stay on. thats a bit extreme. I don't do that. but some do.

just get it balanced again. when you re-install... hand tighten all in a star pattern, then tq it in a star pattern.

its almost certain that its not the alignment.

986speedster · 02-26-2008, 04:33 AM

Thanks for all the advice. I have the same wheels as DJOLMAS..Eurotechs. I suspect if he didnt have a problem, I shouldnt. I will have them rebalance. I dont have spacers, and the tires are going the right way. Again, thanks for the quick response.

D.L. · 02-26-2008, 06:33 AM

I put 19's on my car, and had the same vibration issue. After having it rebalanced on a Hunter road force wheel balancer, it took all the vibration out and it rolls smooth as glass at all speeds. To have the wheels road force balanced should not cost very much. Try that first, and if that's not it, keep problem solving. Road force balance is cheap to do.

chaudanova · 02-26-2008, 09:51 AM

Quote:

Originally Posted by D.L.

I put 19's on my car, and had the same vibration issue. After having it rebalanced on a Hunter road force wheel balancer, it took all the vibration out and it rolls smooth as glass at all speeds. To have the wheels road force balanced should not cost very much. Try that first, and if that's not it, keep problem solving. Road force balance is cheap to do.

DL, just curious, what kind of prices are they charging you in your neck of the woods for the Hunter Road force balancing? Over here, I believe it is around $15 per wheel.