Bumpy Ride !

[Bumpy]

The problem I have is a vibration coming from one front wheel / tire.
It comes about 60 kph til 80 kph and the steering wheel shakes back and forth.

I assumed the problem began when my daughter hit a series of pot holes on a street where they were repairing the pavement around drains and man hole covers.

Upon inspection I expected to discover a bent rim but after several close inspections I can't see any.
I put on another set of rims / tires and the vibration went away.
Next I re-installed the wheels on the opposite side of the car and the vibration returned.

Lastly I removed the offending wheel and am currently running the stock rim / tire in it's place with no issues.

Thinking it might be the tire (a Michelin Pilot SS)
I jacked up the car with the offending tire in place, and then lowered the jack just enough to make slight contact.
This produced an area on the tread that would scuff on the cement floor. The scuff is about 10 inches long and is only along one rib of the tread.
Just a visual inspection would not expose this slight defect.

So I am investigating rims and a replacement tire but am not sure what I should do next.

Can anyone offer me some advice ?

Bumpidy Bumpy

[GAZA62]

Have you checked to see if you have lost a wheel weight as a few years back on my last car I hit a pot hole with same symptoms checked all sorts as it felt so bad in the end it was a ten quid fix had lost a weight off front wheel

[ronk]

You say that the car might have hit a pothole?

Have a look at the tyre wall - I had a problem several years ago on a Volvo when the tyre appeared to be ok but when spun up, a bleb appeared !

[Bumpy]

Update ...
I have 3 sets of rims / tyres.
The stock 241's with Bridgestone Runflats.
A set of Michelin snow tyres on 17" Moda Rims.
And finally a set of Michelin PSS on 18" Lorenzo Rims.

The plan so far has been to use the runflat set when touring out of town.
The Michelin PSS set for 3 season cruising.
And the snow tyres in the other season.

With my bumpity bump problem I spent alot of time just trying to 'see' the damage.
The suspect rim and tyre looked perfect.
I even swapped sides to confirm the location of the vibration.
So in frustration I installed the Bridgestone runflat rim and tyre.
Vibration went away but I was left with a mismatched set on one side.

With my patch work solution in place, I procrastinated in taking the offending rim into a tyre shop, while I spent hours considering a new set of rims (108's or CSL Reps) or just replacing the front PSS's with new or used.
Not sure if you Brits have Kijiji - It's a free buy and sell internet site - You know I was on that more than I will admit.

With winter coming and another tyre change in the offing I got ambitios and tried again to locate my "problem"
I had already had the rim re-balanced (It was OK)
So I put the bad rim back on and lowered the jack just enough to make contact with the garage concrete floor.
Then I spun the tire around, noting where and how much out of round things were. I marked the location with duct tape.
Next I frigged around with the lug bolts to see if I could minimize the non-concentricy of the assembly. That means I lowered the jack just a little on the high spot with the rim just snugged and I was successful in a slight correction.
I also upped the air pressure in the tyre from 30 psi (as recommended by Tire Rack) to 33psi (as recommended by BMW)

You know what ?
Yup ... Bumpity bump is gone !

Side Bar
The offending Lorenzo Rims have a centre bore of 74mm. BMW Hub comes in at 72.6 mm (Dim from memory)
The Tire Rack included some paper thin plastic shims to ensure concentricity (if that's a word) .
The shims lasted one season and I disguarded them the next season with no ill effects noticed.
The bumpity bump arrived at the start of the 3rd season.
I assumed the taper on the lug bolt seats would align the wheel properly.
I guess I was wrong.
So next year I'm replacing the shims with new ones and hopefully that will be the end of it.

End result - Only money spent was for one tyre balance.
And I am a more fit and efficient tyre changer.

Cheers Bumpy

[Bob Byrnes]

I had a run flat tire go bad on my 2004 Z4 this summer. It had a belt separation and the ride was like the flintstone mobile. Had to put on two new rear run flats and now good to go. My little roadster is new to me and only gets "once in a while" use in the warm weather, but, I love driving it. :