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Old 10-25-2005, 03:34 PM
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Question OEM hitch

Anyone know whether the OEM BMW trailer hitch is class 3 (500-lb tongue weight) or class 4 (600-lb tongue weight)?
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Old 10-25-2005, 03:39 PM
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i believe class 3
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Old 10-25-2005, 05:45 PM
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There is more than one definition of the rating.

My OEM X5 hitch was labelled Class III, which I think of as being rated 500 lb tongue weight.

The hitch installation instructions list the following info. Note that this is applicable to my 2003 model, and I believe that the 2005 went to 6000 lbs for the 3.0 automatic (not sure about the 2004). Also, in Europe there is an option for higher towing capacity (I am not sure what they change, but I suspect it is like a shift kit).

All X5:
Max towing weight for trailers w/o brakes (on and off road) 1650 lbs.
Max tongue weight for trailers w/o brakes (on and off road) 330 lbs.
Max towing weight for trailers w/ brakes (off road) 3300 lbs.
Max tongue weight for trailers w/ brakes (off road) 330 lbs.

8 Cylinder/Automatic transmission:
Max towing weight for trailers w/ brakes (on road) 6000 lbs.
Max tongue weight for trailers with brakes (on road) 600 lbs.

6 Cylinder/Manual transmission:
Max towing weight for trailers with brakes (on road) 6000 lbs.
Max tongue weight for trailers with brakes (on road) 600 lbs.

6 Cylinder/Automatic transmission:
Max towing weight for trailers with brakes (on road) 5000 lbs.
Max tongue weight for trailers with brakes (on road) 600 lbs.

Now the caution note. Many people checking tongue weight are thinking about cargo carriers, bike carriers, etc. If this is not you, skip to the end. If so, please consider the following. The BMW specs on the hitch list the maximum drop (vertical) and extension (horizontal) dimensions for the hitch ball. Most carriers significantly increase the horizontal dimension, so the factory tongue rating is not appropriate. You need to consider the bending moment. Also, it is not necessarily just a matter of calculating a straight ratio of distance x weight for a cargo carrier, as most cargo carriers can apply a bounce load. I know a trailer can bounce as well, but it seems to me that it may be a different effect. In any case, the dynamic aspect of high tongue loads can impact not only the rear frame and hitch crossbar, but also the vehicle dynamics.
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Old 10-25-2005, 08:19 PM
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Thanks JCL. I didn't see any spec sheets in my hitch box, and now the packaging is long gone! (Is the info available online somewhere?)

According to the specs you provided, it seems like the OEM hitch on my '05 4.4i would be considered a Class 4/ 600-lbs... Although, I just found my old X5 accessories catalog, and it lists the hitch kit as a Class 3.
Any idea why would the hitches are marked as Class 3 when the accompanying figures indicate that it should be a Class 4?

BTW, your words of caution about the additional leverage to factor-in with carriers make a lot of sense. (I guess that's why Thule's web site requires that you enter your hitch's tongue weight rating when selecting a hitch-mount bike carrier.)
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Last edited by DinanX5; 10-25-2005 at 08:38 PM.
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Old 10-26-2005, 01:48 AM
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Why is it labelled a Class III?

It goes back to there not being an actual standard for 'class' rating of trailer hitches. Or, more precisely, there have been multiple standards. SAE J684-2004 (I don't have a proper copy, I let my SAE membership lapse, but you can Google it), one the hitch manufacturers use called VESC, apparently expired, and another known as V-5, are three of the commonly-referenced ones.

I have seen Class III defined as 5000/500 (Gross Trailer Weight - GTW, Tongue Weight -TW), and also as 6000/500, 6000/600, etc. The SAE J684 standard is 5000/500.

Class IV has been defined as up to 10,000/1000 (GTW, TW), but that isn't the only definition. Sometimes they are rated at 7,500, or up to 12,000, depending on the manufacturer. The SAE standard is 10,000/1000. Some hitch receivers require weight distributing hitches to handle their rated loads.

There are a few different definitions of Class V, but it doesn't seem that there are 'official' definitions.

The above ratings are not considering the benefits of weight-distributing hitches, which help with tongue weight, but don't impact manufacturer's ratings for GTW or gross combined weight (which you will usually run into prior to hitting the trailer weight rating)

Also, hitch ratings can be impacted by the hitch ball dimensions, and the shank size for the hitch ball. A 2" ball would usually be rated 6,000 lbs.

So, after all that, the confusion in whether it is a Class III or a Class IV seems not only possible, but likely.

I think that Class III most closely approximates the X5 maximum capacities of 6000/600. Calling it a Class IV may lead to a belief that it is good for all Class IV trailers, up to 10,000 lb trailer weight. Strict compliance with the SAE standard would mean that a Class IV hitch would be required to reach the 6,000 lb rated towing capacity, but then BMW isn't one of the manufacturers that I would have thought would be close followers of SAE standards (especially since their ratings are in kg).
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Last edited by JCL; 10-27-2005 at 01:35 AM.
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Old 10-26-2005, 02:27 AM
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whats the going price for the oem hitch kit?
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Old 10-26-2005, 12:36 PM
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Would you believe a picture is worth a thousand words? BMW OEM hitch, Hensley hitch interface (weight distribution & sway control), Tongue weight 900+ pounds, GVWR 8,300+ pounds. 2001 4.4i with 75,000 miles, 27,000 miles pulling the assembly.
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Last edited by withidl; 10-26-2005 at 12:59 PM.
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Old 10-26-2005, 02:02 PM
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Um... wow.

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Old 10-26-2005, 06:23 PM
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Quote:
Originally Posted by hayaku
whats the going price for the oem hitch kit?
$450.00 +shipping
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Old 10-26-2005, 08:45 PM
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Quote:
Originally Posted by JCL
Why is it labelled a Class III?
It goes back to their not being an actual standard for 'class' rating of trailer hitches. Or, more precisely, there have been multiple standards...
I see. I suppose it would be too easy if there were just one concise standard
I guess I'll just stick with the 600/6000 figures as a guideline instead of a "class"

Thanks again for the info, JCL
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