Wheel Vibrations/Steering Wheel Shimmining after 50mph

[rb0135]

Hi All,

Long story but will try and cut it short. I have purchased some second hand 19" OEM rims, and had to buy two new tyres (two were already newish, so I got two new ones the same - Goodyear F1 Directional 5 - non staggered 255/50).

These wheels are replacing 20" OEM Rims.

Now, with the 17" rims that came with the car and the 20" I never ever had vibrations (like unbalanced wheels). I have put the 20"s on to test, still no vibration (but creates other issues, so we wont go there, hence the 19" wheels).

However, with the 19", any speed 50mph and over, I am getting a shake/shimming through the steering wheel like unbalanced wheels. Cant feel anything under 50mph and driving above 50mph just causes the vibration to get worse.

The mechanic suggested putting the older tyres on the back. Now the whole car vibrates over 50mph, to the point that I had my golf clubs in the back, and they rattle that much I had to slow down (you can feel the vibration in the seat, floor pan, etc) and similar to driving on a washboard road. Except the road did not have washboard surface and going over the same road testing with the 17" and 20" did not cause any vibrations.

Now, I hear you saying Thrust Arm Bushes, tie rods and that, but the mechanic has checked them out to be A1 and also putting the older tyres on the back causes all this vibration.

So, does it point to the older tyres. They have been put on a balancing machine and are balanced. Not sure what speed they balanced them at (two different shops).

Yes, I could go and buy two new tyres, but they are expensive, specially if they dont fix the issue.

Any ideas to check? Should I try to get the Tyre place to show me what happens on their balancing machine by spinning up to 50/60mph. Can a tyre have an issue above a certain speed (never happened to me before in 30+ years of driving). Anyone have similar issues with one size rims causing no vibrations and another size causing vibrations.

Any ideas greatly appreciated.

Thanks,
Rob