Wheel balance, road surface or both?

[ruaricoles]

Hello peeps,
Our 1994 500 (non PAS) suffers from a steering vibration at from about 75mph+, a little irritating on motorway runs, which I thought was just wheel balance until on a new smooooth section of M5 this weekend when I could barely detect anything at all, ditto on some of the M1. On most of the M40 it's terrible though. Never having had imbalanced wheels on a car before, can the effect of slightly imbalanced wheels be massively amplified on certain road surfaces while not detectable on others? Tyres are SO2s, properly inflated and not flat spotted as far as I know....
Ta,
Ruari

[2 Smokin Barrels]

I'd get the wheels balanced as a starter..it's a fairly cheap process.

[Big_M]

Check tyre pressures first (if you hadn't already), then get the wheels balanced.

Usually steering wheel wobble is front wheels, if you can feel vibration through the seat it is rear wheels.

Could be worth getting the wheels laser aligned at the same time. Costs about £70-80. Certainly noticed the difference on our Griffith.

More expensive vibration causes include driveshaft wear.