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Run Flat tires handling?

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I just acquired a 2003 Z4 with runflat tires, and it wanders badly at highway speeds. I’ve had the steering mechanisms checked (bushings, etc.) and all is well. Can runflats cause this? Can I replace them with regular tires? Do I have to replace the wheels? The car only has 37K miles, and is otherwise a “mid-life crisis” dream. It handles incredibly well on corners and there is no play in the steering wheel.

How old are the tires? If they are original, you might just need to replace them because of age. They are 10 years old now. Also, what brand and model tires are they?

If you haven’t already done so, check the alignment (might not have been checked when they checked the bushings).

Unless the tires are following the grooves in the pavement, tires are NOT the problem here - runflat or otherwise.

Thanks. The tires are Bridgestone Potenzas - rear tires are new, fronts are about 1/3 worn, don’t know the miles. I had the car aligned as part of the steering check.

I could rotate the tires and put the new ones on the front. I don’t know if they were rotated when the new tires were put on, or if they were rotated correctly (dealer put tires on prior to purchase).

Have an alignment done. And have this 9 year old chassis checked over.

Also, do you know anything about the history of the vehicle? Is there a possibility that it was in an accident?

CarFax - for what that’s worth - says the car has only had routine maintenance, no accidents. The previous owner agrees, however, she is the mother of the guy that owns the dealerwhip. So…I wouldn’t bet too much cash on either of those opinions. I don’t see any evidence of body repair on the undercarriage, not that I necessarily would.

I will have the chassis checked, and also will try the two new tires on the front instead of the rear. I assume runflats are like radials, RR to RF, LR to LF.

Thanks for the comments and advice.

Is there a concern about having an alignment done? If so, post it and we’ll discuss it.

CarFax is only useful when it reports a problem. When it doesn’t, you still have to get it checked out. I seem to remember some of these BMWs having rear suspension issues, make sure they check for that.

@mountainbike - I had it aligned right away, so I think it’s good there. Tires are wearing evenly. Also, it doesn’t pull one way or the other, it takes off either way with a mind of its own. It’s not dangerous, just annoying. I’ve had other BMWs and they did nothing like this.

@texasas - I will have the rear suspension checked. I hadn’t thought of that.

Thanks for posting back.
Have you tried BMW Z4 forums? Sometimes specialty cars like this have eccentricities that become known within their peer group but not among the general public.

The Nissan 350Zs, for example, had problems with in inner edges of the tires wearing out prematurely and with the oil getting hot. Both issues were solved with TSBs, but the general public is unaware that the vehicle had them.

@Fritzer - I checked, it was the Z3 I was remembering, cracked rear suspension mounting points. But have the rear suspension inspected, with IRS it can cause just as many handling problems as the front suspension.

A BMW forum is a good idea, as thesamemountainbike mentioned. You can also go to tirerack.com and look at reviews for the type of tire you have. You can narrow it down to people that have your tire on your type of car and see if anyone else experienced this problem.

I WOULD rotate the tires. It is safer to have those with better traction on he rear, but. I would do it to see how much it altered handling. I would do this before I bought new tires. If nothing is gained, you can eliminate those as a cause. Secondly, if it was recently acquired from a dealer, I would work with them and expect them to help rectify the situation including having them spring for a new set if that turns out to be the problem.They may know more then they are letting on. If it takes off either way, it could be dangerous. A call to a factory technician, not dealer, wouldn’t hurt either.

Thanks - great advice. The dealer has been really great working with me.

@texases - I will have them checked – THANKS!

@the same mountainbike - took it to a BMW dealer and had it aligned. The rear tires were out of line. Now fixed, it drives great. Thanks for the push to get this done.

Thank you for the feedback. It’s nice to know what the end result is.
Often the simple things are all that’s necessary and we fret needlessly. I always like to start with the basics.

Happy motoring.

One more thing, check the return hose for the power steering to see how hot it is getting. If you can’t touch the hose after driving on the highway, then the problem could be in the rack.

There’s a nice object lesson here: While it was reported that the vehicle alignment had been checked when the bushings were changed, the fix was the alignment. We just can’t assume everyone does what they are supposed to do.

“The rear tires were out of line. Now fixed, it drives great.”

For some reason, many people forget about the importance of proper alignment of the rear wheels with cars that have IRS.

When I picked up my 2011 Outback, I quickly noticed that a disturbing amount of steering correction was needed in order to keep the vehicle from wandering. A check of the alignment at the dealership revealed that the right rear wheel was badly out of alignment, most likely due to someone slamming it into a curb when backing it off the transport trailer. Proper alignment made the car completely stable.