[Mike Thompson]

F25, issue when towing caravan, engine appears to stutter, miss fire type symptom. Also at slow speeds and when changing up gears without caravan. No errors or engine management lights or indications. BMW diagnostic testing showed no faults indicated.
I have heard this could be tyre wear that is affecting the performance.

[scostu]

Originally Posted by Mike Thompson

F25, issue when towing caravan, engine appears to stutter, miss fire type symptom. Also at slow speeds and when changing up gears without caravan. No errors or engine management lights or indications. BMW diagnostic testing showed no faults indicated.
I have heard this could be tyre wear that is affecting the performance.

Need info from you to help.....

Engine type?
Mileage?
Tire type?
Vehicle well serviced?

[Marty in NY]

Originally Posted by Mike Thompson

F25, issue when towing caravan, engine appears to stutter, miss fire type symptom. Also at slow speeds and when changing up gears without caravan. No errors or engine management lights or indications. BMW diagnostic testing showed no faults indicated.
I have heard this could be tyre wear that is affecting the performance.

Which version X3 do you have? 4 or 6 cyl? S or X? When you say..."engine appears to stutter, miss fire type symptom" is this something you only hear or do you feel it, is it a mild or aggressive stutter? What does your tach do during the stutter? If you feel it, where do you feel it from? Steering wheel, seat, center console, etc. Why did someone think it might be your tires? Are they quite worn? Just trying to help

[383vett]

Again, miles, plugs?

[e30lover318i]

Check Your motor mounts, if you do a lot of towing you could have a broken one causing odd vibrations.

[Mike Thompson]

3 litre diesel M Sport
54,000 miles owner from new
Full BMW service history
Tyres Bridgestone all round
Front 6 mm
Rear 4 mm
It is a stutter, when pulling through the gears.
Rev counter shows no sign of dipping etc.

[scostu]

Originally Posted by Mike Thompson

3 litre diesel M Sport
54,000 miles owner from new
Full BMW service history
Tyres Bridgestone all round
Front 6 mm
Rear 4 mm
It is a stutter, when pulling through the gears.
Rev counter shows no sign of dipping etc.

ZF8 auto transmission?

[383vett]

Any chance you have a bad tank of diesel with water?

[Mike Thompson]

Swapped front wheels and tyres with the back ones, issue resolved, even test with caravan in tow no problems encoutered

[Marty in NY]

Originally Posted by Mike Thompson

Swapped front wheels and tyres with the back ones, issue resolved, even test with caravan in tow no problems encoutered

Really? Interesting, so what is the diff between the front and rear tires?

[383vett]

So it was a vibration, not a miss?

[Mike Thompson]

2 mm difference on front tyres, swapped with rear wheels

[Marty in NY]

Originally Posted by Mike Thompson

2 mm difference on front tyres, swapped with rear wheels

So apparently the front tires had 2mm less tread depth than the rears, right? and when towing, that made the difference? Meaning the X3 was using the fronts (and the rears) to pull with but with the rear load it must be that the front of the cars suspension had dropped enough that the front tires could not get full time traction and what you felt was the slipping of the tires. Correct? So what is the tread depth of those front tires?

If memory serves me well, something like 1.6mm is the minimum legal depth in most states which is around 2/32".

[Mike Thompson]

The tyres on the front of the X3 have 5mm tread and the rear tyres are 7mm.
No issues with this set up.

[Marty in NY]

Originally Posted by Mike Thompson

The tyres on the front of the X3 have 5mm tread and the rear tyres are 7mm.
No issues with this set up.

I find this very bazaar, not sure what to really make of it. Even 5mm should be ok on the front. 2mm is like 5/64", I can't see how that made any difference. I wonder if there is something else going on that changed when you swapped the tires? Where the front and the rear tires new when you installed them? How many miles are on them now?

[e30lover318i]

It means the tires aren’t balanced/worn or bent rim. The vibration is probably still present just not as noticeable when in the rear as your not feeling the vibration in steering wheel.

The best and easiest way to check for in proper balance is to find your speed you have a vibration at and accelerate, if the vibration goes away it means something is unbalanced. A worn universal joint can also cause these types of vibrations but usually you will feel in the seat

[Mike Thompson]

A Master Technician from BMW first suggested that it was worn tyres and said that he had seen this before. I discussed this with a workshop manager from BMW who also confirmed that this could cause issues as all measurements are gathered from wheel speed sensors, which are then used to compensate any wheel slip or lack of grip using the X Drive train system.