XSeries-forum

So, not so long ago, seeking better ride quality (and as my existing Bridgestones were on their last legs) I made the judgment call to purchase some non * marked, non RFT tyres.

Having the 7 seater meant that I needed the ones that could handle the extra weight - 19" 107 at the front and 111 at the rear (staggered setup).  This meant that the only tyres I could find that were of the right size, load and speed rating were Hankook Ventus Evo 2's from Tyre Leader (£500 delivered for all 4).

Upon arrival I measured the tyres (front vs rear) and even put them side by side with a spirit level and they were bang on the same, so I felt pretty confident.

Tyres were fitted and all seemed great.  The difference in ride quality was excellent, soaking up bumps that would've been a pipe dream before.  This was for the first couple of weeks, but then weird things started.

To begin with I noticed it as what can only be described as a "shunt" when braking and coming to a stop, or at least low speed.  It felt like a very aggressive downshift by the transmission and so I started looking into this as a possibility, resetting transmission adaptation values etc but to no avail.  The more I drove the car the more it felt like something "releasing" or "letting go" as the vehicles speed reduced.

Additionally (and this was what gave the game away) I noticed at lower speeds and when turning or doing things like parking maneuvers there would be the occasional mild shudder felt through the car.  Not all the time, just now and again.  This was on top of how the car felt like it was misfiring or coughing when at low parking speeds on and off gentle throttle, even when going straight - like the aforementioned shunt but repeatedly.

It definitely wasn't right.

The coincidence with the fitting of the tyres and the nature of the faults started to add up - it had to be the tyres.  Plus a call to the independent BMW specialist I use added further weight to it saying the symptoms matched what they'd seen on similar X3's - the transfer case wasn't happy. 

They explained that the loss of the RFT meant that the sidewalls were (intentionally) giving more than before and as such would confuse the traction control, which in turn affects the 4x4 system as it thinks the car is losing traction. RFT's maintain this regardless of weight and largely pressure so RR is maintained front and back, despite tyre width & weight differences and pressures, at the cost of ride quality.

So this morning I got my car in for a full set of 4x * marked Bridgestones sharpish in the hope I'd not done any lasting damage.  As I say the symptoms were subtle but noticeable and the sooner the tyres were changed the better.

Upon driving the car away I could tell straight away things were ok again.  Gone was the weird shunt when dropping down the gears or maneuvering at lower speeds, and gone was the weird random (and slight) shudder when turning. Back however was the harsher ride, although not as bad as I remember so maybe the newer Bridgestones are improved over the old ones?

So, I guess my story is testament to the theory that * marked tyres do indeed make a difference, at least in my case, guaranteeing rolling radius not through manufacturing techniques but also through their rigidity in the case of RFT's.  It might only be a thing affecting staggered setups, and possibly more of a risk on smaller wheeled cars (less rim & more tyre making up the overall rolling radius) but my experience was clear. 

I now have a set of 4x three week old Hankooks in the boot of the car which will be going on eBay shortly to recoup some of the cost........

Thank you for the write up and detective work.  Very useful for others on the Forum.

So from what you are saying you can have 4 identical tyres and have no problem. Do the rear wheels accept tyres the same size as fronts.??


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They do, but they need stretching which may affect handling - as well as making you look like a Saxo driver 

The evidence on here points at square setups being fine with any rubber fitted, staggered set ups are the ‘at risk’ category, and not just on BMWs (Merc, Audi, Porsche amongst those with make specific rubber - and not just on high performance models).

It’s strange how it all works as I’m running a set of non runflat budgets and all seems fine.


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Thank you for the detail write up.

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Is yours staggered set up also?[quote="Digidick"]
It’s strange how it all works as I’m running a set of non runflat budgets and all seems fine.


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[/quote]

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Yes they are and in 20” style 333.

I’ve got genuine wheels with Dunlop runflats in the garage and a trial set of replicas fitted with budget Runflats and both currently run the same with no issues, non Runflats obviously giving a much better ride.


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[quote="X5Sport"]
They do, but they need stretching which may affect handling - as well as making you look like a Saxo driver 

The evidence on here points at square setups being fine with any rubber fitted, staggered set ups are the ‘at risk’ category, and not just on BMWs (Merc, Audi, Porsche amongst those with make specific rubber - and not just on high performance models).
[/quote]
So need the get matching Bridgestones with 315 size. I was thinking of keeping all the same size to prevent problem. Not sure what I’m gonna do with rears as they look new.
I also have 18 winter tyres/wheels which came off my 7 series. Can they be put on the X5 for winter snow.
Think the size is 245/50/R18 all round.


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You’ll need to check brake clearances and that the 7er wheels can cope with a 2.2T vehicle.  The 7er isn’t exactly light so may be OK.  Offset will be another thing to watch for in case they sit too close in and impact the wheel arch or suspension.

Any idea what style they are?

[quote="X5Sport"]
You’ll need to check brake clearances and that the 7er wheels can cope with a 2.2T vehicle.  The 7er isn’t exactly light so may be OK.  Offset will be another thing to watch for in case they sit too close in and impact the wheel arch or suspension.

Any idea what style they are?
[/quote]
The offsets are 30 for 7er 18x8j  and for X5 it’s offset 46. 18x8.5j
Will that work with spacers etc??


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[quote="X5Sport"]
You’ll need to check brake clearances and that the 7er wheels can cope with a 2.2T vehicle.  The 7er isn’t exactly light so may be OK.  Offset will be another thing to watch for in case they sit too close in and impact the wheel arch or suspension.

Any idea what style they are?
[/quote]
The wheels are the se type not sport .


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My symptoms were subtle but definitely there and it's possible that a combination of the extra 7 seat weight and bigger profile tyres on smaller rims doing more of the "work" made the car not quite like it much?  I mean like 19" vs 20" or above - you could definitely see the sidewall bulge on the non RFT's even with pressures carefully set so they undoubtedly had more give which you'd expect.  I'm clutching at straws I know....

We're not talking 4x4 style crabbing when turning but the funny shudder now and then when turning/ parking, and the definite shunt when coming down the gears at lower speeds made me concerned. 

The ride quality was certainly improved with non RFT's and I do miss that, and it was also less fidgety at m'way speeds.  Shame.  :noexpression:

Others have reported shuddering at low speeds in full lock, so what you experienced makes sense, and doesn’t sound at all like ‘clutching at straws’ from an engineering approach.

BMW do offer non-RFT tyres for winter use that are ‘*’ marked but only for square setups (including winter tyres).  You may have picked up on something that is actually significant and additional to tread depth.

So, it okay to assume that having non RFT on a non-staggered set up might be fine with no adverse effects? [quote="X5Sport"]
Others have reported shuddering at low speeds in full lock, so what you experienced makes sense, and doesn’t sound at all like ‘clutching at straws’ from an engineering approach.

BMW do offer non-RFT tyres for winter use that are ‘*’ marked but only for square setups (including winter tyres).  You may have picked up on something that is actually significant and additional to tread depth.
[/quote]

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