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[E90X3]

I need your help !

I have read the posts of the RFT wandering or tramming and experiece this - but also at highway speeds experience an even more disconcerting thing that never happened on my old e46.

when driving over bumps in the road - especially the bumps from contracting concrete that run perpendicular to travel - the steering wheel seems to want to go somewhere else suddenly- so much so that now when driving I hold on to the wheel with both hands tightly to prevent the wheel from bouncing out of control.

it almost feels like a bicycle where if you go over a bump the front wheels "lands" in a slightly different angle - and the wheel is no longer going in the same direction.

any ideas if this is a function more of the run flat aspect of the tires or is it the "high performace" low profile attributes of the tire ?

The car is not relaxing to drive on the highway like my old e46 was - I miss my old car more and more.....

[Brunotheboxer]

imo, it sounds like something could be wrong with your car if this is so severe. maybe out of alignment or a front wheel is out of balance. on my 330i i dont feel this at all. i would take the car to the dealer and have it looked at.

[LEDZEP]

I experience the same "hopping" under certain road conditions and speed. Particularly noticable are areas where the road is in disrepair or has poor joints on a curve. I'm afraid there isn't much we can do to change the laws of physics for this. If you are driving through a curve and hit bumps or unlevel joints in the road your wheels are going to "hop". Normally this is just a bump. Your front tires become airborn (albeit for a split second). Cars cannot turn when they are airborne, so for that breif moment your front tires are not steering the car and it goes "straight". When the tires regain contact with the road, the angle of turn of the wheel is out of sync with the current direction of travel. The tire grabs the road and corrects your movement, but this feels uncomfortable and jarring. The faster you're going, the worse that will be.

There are a couple of spots like this on my daily commute, and I tend to slow down to reduce the problem. It's also not good for your tires if that happens a lot. It is possible that the stiffer RFT's will make this more pronounced, but the problem is poor road maintenance and design and physics.

[prust]

Check the air pressure in your tires. When I picked up my 330xi and drove it home I had the same problem. The front tires were at 40psi instead of 32psi. Once I corrected the pressure the problem disappeared.

PR

[findtom]

I get the hopping sensation from the RFTs. I just switched back from the winter tires (not runflats) and I'm really noticing the feeling of the wheels losing contact with the road surface... particularly cornering on bumpy roads (which there are lots of in Quebec). It's kind of annoying I have to say. One thing that helps is hitting the DTC button when you get in the car. It stops the car from killing the power to the rear tires everytime they lose contact with the road.

[Pazzuzzu]

Originally Posted by prust

Check the air pressure in your tires. When I picked up my 330xi and drove it home I had the same problem. The front tires were at 40psi instead of 32psi. Once I corrected the pressure the problem disappeared.

PR

If and when you check tire pressure wait until they cool to ambiant temperature, then go for the suggested pressure. After a drive, it is normal that the pressure goes up as the tire warms.

[pokerface]

I think I may already knocked my steering out of alignment (ever slightly so) after 4 days of ownership.. but I'm not actually sure if I had taken delivery and simply not noticed. I do find the car follows ruts on the road a lot easier compared to previous vehicles (all 16 inch rims)

[T-MC-G]

Originally Posted by E90X3

I need your help !

I have read the posts of the RFT wandering or tramming and experiece this - but also at highway speeds experience an even more disconcerting thing that never happened on my old e46.

when driving over bumps in the road - especially the bumps from contracting concrete that run perpendicular to travel - the steering wheel seems to want to go somewhere else suddenly- so much so that now when driving I hold on to the wheel with both hands tightly to prevent the wheel from bouncing out of control.

it almost feels like a bicycle where if you go over a bump the front wheels "lands" in a slightly different angle - and the wheel is no longer going in the same direction.

any ideas if this is a function more of the run flat aspect of the tires or is it the "high performace" low profile attributes of the tire ?

The car is not relaxing to drive on the highway like my old e46 was - I miss my old car more and more.....

I know exactly what you are talking about. It sucks, my old e46 didn't do it either.

[E90X3]

thanks for all your comments ! I called the service center today - and he said it is the low profile 225/45 17 that is causing the hopping and not the RFT factor ? comments ?

perhaps the RFT exacerbates the situation ?

Having 16" wheels on my old e46 - I am lost as to if it is the low profile or the rft causing "more" or the hopping....if it's the rft I can switch tires - if it's the low profile not much I can do ?

[prust]

The profile of the tire and the specific tire both seem to have something to do with the way they react to the road. Prior to my 330xi, I had a 540i sport with 18" wheels and 235x40s in front and 265x35s in the rear. These were not run flats but were pulled from side to side by groves in the road. They did not hop. When I put 235x45s winter tires on the car was fine. The 330xi has 45 series tires, the same as my 540 winter tires and I have not had a problem since setting the pressure correctly. They did hop severely when over-filled.

PR

[Carnage]

Originally Posted by E90X3

thanks for all your comments ! I called the service center today - and he said it is the low profile 225/45 17 that is causing the hopping and not the RFT factor ? comments ?

perhaps the RFT exacerbates the situation ?

Having 16" wheels on my old e46 - I am lost as to if it is the low profile or the rft causing "more" or the hopping....if it's the rft I can switch tires - if it's the low profile not much I can do ?

I'm not buying that "excuse". I had the same issue and it disappeared when I put on non-rft winter tires of the same size. I'm running 235/35/19 and 265/30/19's now and based on the service center's "low profile" theory, the problem should be worse. The problem doesn't exist now.