Front tires question

[WTL]

I recently had the dealer mount and balance 2 new front tires - Michelin Pilot PS2's - 235/35/19's.  Please see the attached note on the work order.  This past weekend was the 1st opportunity I had to take it out on the highway and i noticed shaking in the steering wheel from about 55 on up and a more noticeable vibrating which seems to be coming from the middle of the car.  Called dealer and they recommend 500 miles highway use to see if they settle in.  They explained that they have seen some warranty issues on the Michelin's.    Can anyone explain the road fore weight statement?  Ive never heard of that before and never had problems with any tires,michelin or otherwise.  Tks.

 

 

Edited November 26, 2019 by WTL

[Loren]

Sometimes rotating the tire on the wheel can change or fix balance issues. If you put the heaviest part of the tire on the heaviest part of the wheel (usually by accident) chances you will have an balance issue.

 

Here is an article/brochure that explains more...

4159-T.pdf

[WTL]

tks.interesting article.  Anyhow, drove the car again to verify shaking....  Michelin was nice - talked to them to get some info and they told me to return the tires and get what i had originally asked for - OEM tires.  On order. 

[Loren]

[Mijostyn]

Hi WTL, 

Balancing wheels for 911's is an art that most techs do not understand. Having learned that the hard way I bought my own balance machine (a Coats) about 25 years ago and have been balancing my own tires ever since. I am not enamored with Road Force Balancing. I have a friend with a BMW Z8 who had a similar situation to yours. I balance them to under 0.1 OZ and the car ran beautifully. Here are several tips, things to watch for when your wheels are balanced.

The tires must be warm. The tech should drive the car around the block and put it right up on the lift. If the car sits for more than 30 minutes the tires will flat spot and will be "unbalanced."

      I put my car up in the evening when I get home and balance the tires the next day. 

The wheel mounting surface must be absolutely clean. A good tech will wipe the surface and center hole with a Scotch Bright pad. I also spray the surface with Bostech Glide Coat along             with the centering cone and balancer flange. 

The machine has to be taken off "round off" mode so that it reports weight in hundredths not in 1/4 Oz increments. When a machine in "round off" mode reports "0 Oz" what it really means  

     less than 0.25 Oz. A weight of 0.24 Oz will be reported as "0 Oz" Not good enough for a 911. You have to get it down to less than 0.1 Oz. 

The tech has to lock the wheel down and spin it several times to make sure he is getting consistent readings. it is VERY easy to miss mount the wheel and unbalance it. Just a spec of sand  

     will do it.

The tech should initially mount the weights with packing tape so he can move them around to get it "just right." The best techs will use 3M Wheel Weight Tape now as you can cut it to any             size. It is difficult to cut the new steel weights into sections less than 1/4 Oz. 

 

A 911 with perfectly balanced wheels is a beautiful thing. Loren is quite right about matching the tire to the rim. Mounting low profile tires is another pain altogether. The machines that will do it without dinging your rim are way beyond my price point. I use a fellow who has a Corgi touch less machine. 

 

Mike

 

[WTL]

tks for the follow up.  I ordered the oem tires they originally told me they dont make anymore and the dealer removed the out of balance ones and put the new new  ones on.  all good now.