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      09-02-2011, 10:55 PM   #2
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Quote:
Originally Posted by arcticdog View Post
Hi all,
This is my first post on this forum. I recently took delivery (the day before hurricane Irene landed here ) of a 35i (jet black/mojave/wave, sport activity, cold weather, dynamic handling, premium, nav, hi-fi, apps). In brief, I am appreciating the evolutionary progress BMW has made in this edition (I've gone through an '05 auto and '08 manual) with greater refinement, smoothness, and quality.

Anyway, being in the northeast, as I've done so with my previous X3s, I will be swapping out the stock wheels/run flats with a set of winter wheels/snow tires for the winter. I can't seem to find the torque value for the lug bolts in the PDF manual ("torque - lug bolts" is not even listed in the index! For the '08, the manual did state 101 lb ft/140 Nm, and that was for the standard 17" OEM wheel.)

A quick search for lug torque on the forum here shows people saying "89 lb./ft." and even a range of "between 85 and 101 lb./ft."

Does anyone know the exact correct torque value of the lug bolts for the F25 35i's 18" OEM wheel? Thanks. It's no fun having a wheel wobble off while at speed!
First, welcome to the Forum. You will find a wealth of information here as well as many, many "opinions".

The "nominal" value is 89 lb./ft, but any value within the range of 85 to 101 is acceptable. As I recall, those values came from a translation/conversion from the German Owner's Manual. Any value you set with a torque wrench will likely have an error associated with it. The best "analog" torque wrenches (bending beam) are accurate to about +/- 5% and the very best ($200 and up) digital wrenches (Gearwrench or Snap On) are accurate to about +/- 3% or so when recently calibrated.

That "nominal" torque reading is for clean, dry, but NOT greased or oiled lug bolts only.

Also, because of the bolt thread pitch as compared to the E83, (M14X1.25 compared to M14X1.5) the actual bolt tension (and the force holding the wheels to the hubs is 20% higher on the F25 chassis. A F25 bolt at 89 lb./ft. is actually putting more holding pressure on the wheel than a E83 bolt at 101 lb./ft.

As always, it's best to approach the final lug bolt torque reading in a couple of stages. IE: First torque all bolts to 10 or 20 lb./ft, then all to 50 lb./ft. and finally all to 89 lb./ft. in a standard "star" pattern.

Of course, with alloy wheels, some settling-in due to "cold flow" always occurs. Most wheel manufacturers recommend re-torquing the bolts after 500 miles, but hardly anyone but serious racers ever do it.
Appreciate 2