Tires: BMW 19 Tire Problems, cooper zeon tires, 18 rims

Question
Barry,
I have a 2004 BMW M3 that came with 18" rims.  After the OEM tires wore out I decided to replace 18's with BMW OEM EVO style 19" rims and upgrade tire size accordingly.  I went with Cooper Zeon tires, 255/35/19 for the rear.  BMW called for 225/40/19 for the front but not many manufacturers make this size so I used a conversion chart and found a less than 3% difference fit, 245/35/19, this allowed me to get a full set of Cooper Zeons.

So I had them installed by a large chain tire place, someplace I've dealt with a long time and always thought they do very good work.

The front end now feels a little squishy on handling and more importantly there is vibration in the steering wheel at high speed.  I have taken the car back in twice now and they have rebalanced but the problem remains the same, the faster the speed, the worse the vibr. The front also pulls to the right but the shop ran the alignment twice and showed me the chart.

I am trying to figure out where else to look for the problem. There was no vibr or pulling before I put these new tires and wheels on. Could the wider fronts I put on be causing this kind of problem or would it have to be a defect in the tire if it is not the balancing?  I ordered the tires online but the shop did not think there was any obvious problem with the tires themselves.  Would a problem that caused vibration be obvious to the eye?

I am thinking of just getting two new Michelin PS2 for the front in the exact size called for and checking with BMW to see if there is anything else in the car that has to change to use 19s instead of 18s.  I am trying not to just throw money at a problem that I do not understand.

Any help greatly appreciated.
Thanks,
Gordon  

Answer
Gordon,

As you have discovered, if you have a problem with tires ordered on line, you don't have a place that is willing to take responsibility.

Plus there are some pitfalls that you only learn if you've done this type of stuff before.

The first thing I would do is swap the front tires side to side.  If the pull changes, then its the tires that are causing the pull and should be replaced.  If not, then its the alignment.  And "in spec" is not good enough.  The allowable tolerance should be half of the published value.

The vibration issue is a bit more complicated as the vibration could be the rims or the tires being out of round.

Hopefully, the big chain you went to has a Hunter GSP9700 road force balancer.  If not, find one:

www.gsp9700.com

Someone who knows how to use the machine ought to be able to sort out if the tires or the wheels are the problem.

And here's one of the things you learn when you do this over and over again.

Did you get the hub rings?  You need to check on this!

Hope this helps,