04-04-2018, 01:59 PM | #1 |
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Issues with non run flat tyres on Xdrive
So guys I’m just about ready to order some new tyres for me 35d Xdrive. I have just read a post on a fb page that a member has put mps4s on from run flats and issues have started
Can anyone shed some light does the Xdrive not like different tyres or is this just pure coincidence? There were three areas I was keen to improve on performance wise on my Dec 2014 335d. Speed, Handling, Grip. Nothing track orientated, just moderate road use and keeping the car economical, legal and as a daily driver. Anyway it’s worth reading the following if you have XDrive. Tyre & Wheel Sizes (OEM) Front 225/40/19 - ET36 8J 403M Rear 255/35/19 - ET47 8.5J 403M SPEED - this was achieved by a stage 1 remap at DMS and resulted in a very smooth broad torque curve and 391.2bhp. Excellent. HANDLING - this was achieved by fitting ACS springs, roll in corners reduced, comfort improved! and looks so much better with a 25mm drop all round. Still fairly soft in my opinion but with Adaptive Suspension set in Sport it is very good. Didn’t feel boaty now, It’s no M3 but they are completely different awesome beasts. GRIP - this is where the problems started, had MPS4S non runflats fitted and the car immediately felt ‘bouncier’ still handled well but over big dips and general feel it felt ‘bouncy’... however the main problem was when fully warm every seven seconds or so the car would ‘surge’ for a second, a few hundred rpm ‘blip’. Not every time but around half the time. Just put BMW starred 19” tyres Bridgestone Potenza S001 BMW starred tyres on and the car feels planted and no surging! Basically is this a rare isolated case or something else going on here? The Michelin MPS4S tyres are back on and have superb grip but the car feels bouncy again and the surging is back. I thought it was the Map but it wasn’t, DMS have been BRILLIANT In helping me source the problem. Question is, is the XDrive that sensitive to tyres, wheels are 403M OEM. Does anyone want a set of MPS4S tyres done approx 2,000miles as on my car I prefer the runflats, the ride is more planted, the grip is probably not as good. Anyway food for thought eh? Any feedback would be great from people running non run flats |
04-04-2018, 02:14 PM | #3 |
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04-04-2018, 02:37 PM | #4 | |
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Some users get away with it, others don't. Reading just this evening, where an xDrive user queried the use of non approved tyres on an F3x xDrive model, (F30 330d xDrive to be precise). The garage had experienced some examples of drivetrain/transfer box issues, users who were running non approved tyres. Some with very expensive repair bills. |
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04-04-2018, 02:42 PM | #5 | |
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04-04-2018, 02:46 PM | #6 | |
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im amazed as to why 4 brand new tyres just because they arnt run flats would cause this issue i have never come across it until now everyone reccomending PS4s to me running xdrive and i was just about to change to non run flats |
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04-04-2018, 02:51 PM | #7 |
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04-04-2018, 02:53 PM | #8 |
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With the amount of people on here fitting mps4's to xdrives in the last couple of years, if they'd all had problems there would have been plenty of moaning but Ive not seen any.
I fitted mine in November to my 335d and not (touch wood) had any problems. As highlandpete mentions most people tend to get away with it and have no problems.
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04-04-2018, 02:55 PM | #9 |
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PS, would the extra torque of the map possibly have an effect on the xdrive when fitting non starred tyres?
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04-04-2018, 03:05 PM | #10 |
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04-04-2018, 03:05 PM | #11 |
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Someone else on here had trouble with surging on a DMS remap, and had the remap removed I think.
I'll check with the technical department at AC Schnitzer about the PS4S, they might have some info. |
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04-04-2018, 03:10 PM | #12 |
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great stuff thanks. just sent my friend a message who is a BMW technician too see what he says
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04-04-2018, 03:15 PM | #13 | |
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We are in the guessing game for longevity, or even immediate problems. It can be a bit of a lottery. Some users have had bunching and strange knockings and juddering, almost immediately after changing tyres, others it come gradually and premature wear can turn to failure. Many users don't appreciate the differences that can exist between approved tyres for the xDrive systems and generic tyres of the same sizes. Tyres are dimensioned to ETRTO standards, but that doesn't mean the Rolling Circumference (RC) is to the tolerances that manufacturers are working with. Approved tyres can be to different specification, tighter tolerances, even sizing and construction, compared to the generic tyre from the same manufacturer. The RC is what matters with xDrive. One tyre type may work OK on the BMW rim sizing, another with different construction and/or characteristics may mean the RC variation 'front to rear' on staggered rims is more than BMW's tolerances. Then there is the grip of the tyres. Any variation in RC 'front to rear' has to be accommodated somewhere. The better the grip from the tyres the more wheel speed compensation has to be absorbed through the transfer clutch pack. Get it wrong and something has to give. |
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04-04-2018, 03:21 PM | #14 | |
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I note quite a few run higher than normal use 'placard' pressures on the front. |
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04-04-2018, 03:26 PM | #15 |
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04-04-2018, 03:28 PM | #16 |
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Yehh people who have posted with no issues have been running 36psi
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04-04-2018, 03:33 PM | #18 |
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04-04-2018, 03:46 PM | #19 |
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I ditched runflats on around 14000 miles, and have now done 108000 miles, the whole of that mileage on MPSS and then most recently on a set of MPS4S. Over winters I've been using non run flat Pilot Alpins.
I've not had any issues of any kind until very recently. On changing back to my summer tyres I noticed that one of my summer rears (MPS4S) has abnormal inner edge wear, yet the winter tyre that came off did not. I did do one track day on that set of tyres last year, so wondering if that caused it, but that never caused me any issues on the MPSS sets I used, so I am booked to get the alignment checked on Friday to be sure. I have also noticed a slight vibration on that set of tyres now, so checking the wheel balance too. A bit of a bizarre one if I'm honest, but who knows, maybe it's a thing with the MPS4S... or certainly when you're remapped, running quite low on coilovers, and 15mm spacers at the rear too. If so then I'd go back to MPSS though, as they were great too, and I would never go back to runflats on that car.
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04-04-2018, 03:54 PM | #20 |
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Probably the map affecting the lock up on the transfer case causing slip skid. Your old tyres have worn to the exact size required to avoid this. New ones are fighting each other until the circumferential difference is worn equal.
Try this, straight piece of ground, mark the bottom of each tyre and place a corresponding mark on the road. Roll the car forward a few revolutions of the tyres until the mark on one comes back to the bottom. See if they are all aligned. If not mark the road where the first tyre reached bottom dead centre, then continue to roll until the corresponding, front /rear reaches BDC. Measure from the start marks to finish marks respectively and calculate difference as a percentage. The issue with tyres is that although they have the usual markings 225/40 R19 etc, they are not always exact, there is a tolerance. Add to that a 255 tyre overinflated will bulge more than a 225 tyre also overinflated. Viola difference in rolling circumference......which AWD systems can't handle. Tyre pressures can be played with to balance the circumference, or my preferred method, remove the front propshaft |
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04-04-2018, 03:59 PM | #21 |
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Hearing all kinds of things with regards MPS4S's. I can't comment on fitting them to xdrives but I fitted them to the rears of my old M3. Massively improved grip and a very good move imo. I had no issues or regrets fitting them.
However, on M3cutters there has been a mixed bag of responses on this tyre. One guy hated them so much he went back to MPSS's not long after fitting them. And a few others liked them and others hated them. Opinion seems split right down the middle, certainly on M3/4's. Very strange to hear so many differences with regards these tyres.
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