Tyres pressure upped, shimmy less? What does this mean?

[Steviesam]

I have a shimmy through the car at 65mph plus, up to approx 85.
Not through the steering wheel at all.

All new suspension etc, but still there. Wheel balanced to zero by a proper pro, shimmy still there.

So yesterday I wwhacked up the tyre pressures to the max load/max speed pressure, approx 10 psi higher than "normal"

Shimmy still there, but much less pronounced.

What do this point to?

Thanks

[Digitalize]

Soft/under inflated tyres?

[jon-]

What tyres? Have they stood a long time? They could be out of round, but my money would still be on a balance issue. There was a good thread on road force balancing here a few weeks ago.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Ozzie Osmond]

Shimmy generally comes through the steering. Try swapping both tyres front to back. If it cures the problem you know the dodgy tyre is now on the back. So next swap them from back to front one at a time and see when the shimmy returns. That's your dodgy tyre.

[mygoldfishbowl]

One of your rear tyres is not round. Pot hole damage etc.

[Goldmember1]

Also what car is it?
1st thing I thought of is the 1-5K Barge Thread where a "shimmy" has been talked about on the older 5 series ( sorry don't know what E, E39 maybe? )

[Triumph Man]

Goldmember1 said:

Also what car is it?
1st thing I thought of is the 1-5K Barge Thread where a "shimmy" has been talked about on the older 5 series ( sorry don't know what E, E39 maybe? )

My first thought was old 5 series...

Everyday I'm shimmying /lmfao

[thatdude]

Goldmember1 said:

Also what car is it?
1st thing I thought of is the 1-5K Barge Thread where a "shimmy" has been talked about on the older 5 series ( sorry don't know what E, E39 maybe? )

My father-in-law also experieinced a constant shimmy with both of his 7-seires BMW's (one was an 88 model year, the other is a 99 model year)...he tried everything on both, reduced it but not eliminated it. The best thing was fitting tyres that were as close to the OEM tyres as possible

[Steviesam]

Its a Merc CLK.

Wheels themselves are totally round and true, no issues there.

I am aware of the 5 Series shimmy, but this is not the same. My front end is perfect.

Only issue with swapping the wheels round is that they are staggered so bigger on the back.

Thanks for the ideas so far.

[Triumph Man]

thatdude said:

Goldmember1 said:

Also what car is it?
1st thing I thought of is the 1-5K Barge Thread where a "shimmy" has been talked about on the older 5 series ( sorry don't know what E, E39 maybe? )

My father-in-law also experieinced a constant shimmy with both of his 7-seires BMW's (one was an 88 model year, the other is a 99 model year)...he tried everything on both, reduced it but not eliminated it. The best thing was fitting tyres that were as close to the OEM tyres as possible

It is soul destroying.

[Pappagallo]

I had one on my E60; turned out to be a non-uniformity in one of the rear tyres, identified by a road force balance (Hunter GSP 9700). This balancing virtually got rid of it completely, but new tyres later on were even better.

[B'stard Child]

thatdude said:

Goldmember1 said:

Also what car is it?
1st thing I thought of is the 1-5K Barge Thread where a "shimmy" has been talked about on the older 5 series ( sorry don't know what E, E39 maybe? )

My father-in-law also experieinced a constant shimmy with both of his 7-seires BMW's (one was an 88 model year, the other is a 99 model year)...he tried everything on both, reduced it but not eliminated it. The best thing was fitting tyres that were as close to the OEM tyres as possible

I had a slight shimmy on an E38 when I got it (on 18's) completely gone on 16's and stayed like that for 7 years till I put the 18's back on

[Ozzie Osmond]

Steviesam said:

Wheels themselves are totally round and true, no issues there.

How can you be sure? It's not all that unusual for a tyre to be "not completely round", in which case no amount of careful balancing will ever solve the problem.