2001 Merc SLK320 twitchy steering.

[myk320]

Hi.

Purchased a SLK 320 back in the summer.
It is a good one mind. VGC. Has been waxoiled several times over its life and engine is sweet. FSH blah blah.

Thought I'd try out some 18 inch AMG alloys as they were a bargain. Fitted with new tyres.

Previously 16" wheels no problems.

Now at 50-60mph and above, steering isn't twitchy but could be translated as so because more effort is needed to keep steering straight.
Not wandering dangerously but constant small corrections needed.

I understand that the tyre size difference will make it tramline more but this symptom occurs on smooth roads also.

Thought I'd ask the question here as there is wheat in my circle but a lot of chaff too.
I'm erring towards the idea that tracking may need readjustment.

Any thoughts greatly appreciated.

Chopping trees down then chopping them up seems an impossible task.

[MickyveloceClassic]

Not sure about your trees, but the car wasn’t designed for 18” wheels.

Put the 16” wheels back on, and all your problems will disappear.

[rlw]

Same offset? If not, it could make a Hell of a difference.

[myk320]

Same offset yes.

[Den Den]

If it was me, I'd get a proper alignment done, preferably at a decent Independent. Whereabouts are you?

[Ian-27xza]

I'd imagine that the ride height will now be higher, depending on whether you've gone for lower profile tyres or had the car lowered to compensate?

The R170 SLKs have a steering damper, which are only about £80 and they do wear out and effectively fail. It's a very easy fix, labour wise. I've replaced one on my SLK 320 and the difference was night and day.

Tyre pressures - these R170s seem to be relatively sensitive to tyre pressures - try playing with these.

For reference for the optional 17 inch wheels were :

FR - 225/45/17 - ET37 (30 psi)
R - 245/40/17 - ET30 (33 psi)

[Dog Star]

Very true about the steering damper. Little lift-o-mat type strut under the car on the rack. Easy and cheap.