10-14-2017, 05:42 PM | #1 |
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Rear axle extremely wobbly with Michelins NRFT SPs
Recently replaced stock 467m for 375m wheels on my 2014 X5 Sports.
Went from 19" to 21" staggered, Dunlop RFTs in the front and Michelin SP NRFTs in rear. Tires with more than 50% tread left. With the change, the rear of the car now wobbles from left to right almost to the point of concern, with road imperfections and increases with speed. Tried underinflating and overinflating tires and no difference at all. Read somewhere that rear suspension is tuned with RFT, but didn't realize that NRFTs would turn the car so undriveable. Any ideas??? |
10-14-2017, 06:26 PM | #2 |
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Do those 375m rims have same hub size? AFAIK rears from x5m/x6m may differ, but I'm not 100% sure on it
If hub size is same and rims are centered on the hub (hubcentric) - then it's your rear tires that are worn and possibly have uneven circumference - thus it wobbles from left to right. If you can jack up each rear tire at a time and give it a spin (probably has to be in Neutral gear) - I'm sure you can see one of them (or maybe both) wobble |
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10-14-2017, 07:50 PM | #3 |
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i thought it wasnt a good idea to mix runflats and non runflats. not sure if that is part of the problem.
many run non runflats without issue. out of curiousity, what sizes are you running? |
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10-14-2017, 09:37 PM | #5 |
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Mixing of tires was due to the Dunlop SportsMax rears going baby butt flat in less than 4K miles. The front ones were in better shape so I had to find rear replacements. Found a pair of Supersports at a good price and that's how I ended up that way.
Sizes on the 21's are the stock sizes, 285 and 325s. These were takeoffs from X5Ms. I stick to the idea that the suspension tune in X5 are for RFTs with the stiffer walls. The wobblyness should be due to the NRFTs softer walls. |
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10-14-2017, 09:58 PM | #6 | |
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P.S. Just to make sure - that X5M they were taken off is a F85 or E70? E70 has smaller rear hub, so if they fit your f15 x5 - that means they were drilled to 74.1mm hub size and hence big chance it wasn't done properly and you have wobbling now. If it's F85 - then it's a non issue Last edited by DuSh; 10-14-2017 at 10:06 PM.. |
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10-14-2017, 10:08 PM | #7 |
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You may have a point there. The rear SPs are not an original pair. One js 10-15% more worn than another. Both close to 59-60%.
They have no repairs or any kind of visible imperfections though. Could this be the real reason? |
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10-14-2017, 11:10 PM | #8 |
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So the xDrive system is sensitive to tires not all being evenly worn (supposedly) but I don't see that causing a wobble.
Were the wheels/tires properly mounted and balanced by a reputable place? Are the wheels straight and true? |
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10-14-2017, 11:16 PM | #9 |
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I had the whole car aligned at the BMW dealership when I moved to the 21's and with the RFTs all around. Since then the rears were replaced with the unmatching SPs.
Does it need a realignment due to the different tires? |
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10-14-2017, 11:30 PM | #10 | |
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If so, then I'm thinking there's an issue surrounding the balancing and mounting of the rears. Who did that work? BMW dealership also? |
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10-14-2017, 11:43 PM | #11 |
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When I had the matching rear Dunlops and had the alignment, there was no such issue.
It all started when I replaced the rears to the SPs. Mounting and balancing was done at a small tire place and there was no realignment done after. Car is going in for service at the dealership next week. I'll ask them to look into the alignment they did ($175!), and see if it needs an adjustment due to the different tires. This got to be the cause. |
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10-15-2017, 12:03 AM | #12 | |
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For what it's worth, I went from 469s to 375s and mounted Michelin Pilot Super Sports on all four corners. I had them mounted and balanced at the BMW dealership, but never got it re-aligned. Drives like a dream. |
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10-15-2017, 01:20 AM | #13 |
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^^^^This!
OP, Swapping tires regardless of RFT or non-RFT will not affect the actual alignment. You?ve already pin-pointed your problem. Everything was fine before you swapped in the rear mismatched tires. So either they weren?t mounted/balanced/installed correctly or the wear between the left/right is a lot more than you think. Could be as simple as the tire shop not torquing the lug bolts all down. I?d take it back to them and have them put the rears on the balancer (while you watch) to see if they’re balanced. Why spend more $$ to have the dealer rebalance before making the tire shop show you first?
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10-15-2017, 08:50 AM | #14 |
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Replaced RFT with non RFT on a 35 with zero issues. I would mot run RFT on the front and non RFT on the rear due to the sidewall difference in the tires.
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10-15-2017, 11:41 AM | #15 |
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10-17-2017, 10:57 AM | #17 |
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Looks as if the issue is narrowed down to either/or 1) bad balancing on the rear MSPs; 2) uneven wear among the two.
At this point I don't feel like going back to the small tire place, so I'll just ask the dealer to look at the issue when it goes in next week. They'll probably rebalance and realign, if needed. Will post results after that. Thank you all for the inputs! |
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10-17-2017, 11:48 AM | #18 |
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I?ll bet that the dealer will give you a ton of grief (or worse, not want to touch it) for mixing RFT with NRFT. Why not swing by and have them confirm/re-balance vs making an appt with the dealer? Mounting/balancing isn?t rocket science so unless the shop is actually shady/incompetent...
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10-18-2017, 07:25 PM | #19 |
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Well, in an unexpected turn of events, I drove down to the small tire place (Mr Goma's - fairly popular in Miami and on ebay), and explained the wobble issue. At first, their inclination was that it was a shocks issue, but after putting the car on the lift, they confirmed it was not a balancing issue (by hand rotating the wheels and seeing they rolled smooth), but rather, a very bad misalignment. Car was then moved to the alignment bay and when they put the wheel mirrors on, alas, completely off toe and camber in both rears.
To my disappointment I realized my PSPs were down to 3/32nds in approx 1500 miles and 45d of use (had not looked closely until now), from when I bought them at 7/32nds. Wasted $400 right there. So I came to a dilemma, did I hold off on doing a new alignment there or did I wait until next week when the car went in for service at the dealer so I could make them realign under warranty. Since it was on lift already and I was down $20 just for the diagnostic, it was another $40 to complete the alignment so I told them to do it. My thought process was dealer was not going to refund my $175 alignment cost and if they were incompetent the first time, no warranties they would do a better job the second time around. Driving home (short distance) after that I was not able to feel much of the wobble, but it's still too early to tell since I did not go fast, hit potholes, or drove in wet conditions. I'll continue testing it out through the weekend. Back to the BMW dealer incompetence: so when they did the $175 alignment about 2 months ago, I remember the dude was scratching his head because for a while he couldn't get it to align correctly. Problem was that with the VIN put into the alignment machine, it was picking up the 19" stock wheel sizes, and that made the computer crazy. He then had to manually override the wheel sizes for the 21" set, and presumably, that got the alignment in place... Whatever happened there, I can probably say it's what started the issue, it was just not done right. The initial readout from today showed the rears in full red and way over toe and camber tolerances (I'm not an expert, so can't comment further). It was all back to green by the time I left. What could've happened at the dealer it's beyond me. I could complain to the dealer saying they killed my tires, but since those were used tires to begin with, I knew I was not going to get anywhere by giving the dealer a receipt for used tires. It was going to be useless. Now, with 3/32nds on the rears, these will last another 2000 miles (at very best and assuming today's alignment cured the problem), before I either put in new $500 tires each, or another 7-8/32nds pair for about $400. It's just been a bad cash bleed with these 21"s. Thanks again for your interest in this thread. |
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10-18-2017, 11:31 PM | #20 | |
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On my X5, when I was excited to mount the 21s, one of the bolts of my 20s ended up being seized and I had to hit three places before the dealership finally charged me hundreds of dollars to carefully remove it. |
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10-19-2017, 12:49 AM | #21 | |
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Also happens when you have hit curb and there's bent control arm - will be same jumpy feeling of rear axle due to misaligned rear wheels |
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