Took the towing (i.e. withidl) plunge...

[Bayerische E53]

Just found the E53 option code. JCL was correct. The option code increases tow capacity to 3500kg (7,700lbs) with a 12% gradient maximum. Actually, the standard towing capacity is also rated at a 12% gradient maximum. The increased towing capacity option was available for the V8 and I6 Diesel cars so I think it's now safe to say that concern here is power rather than chassis strength. As far as the chassis and suspension goes, it looks like the E53 is actually good for 7,700lbs per the manufacturer.

JCL, any input?

See below:

http://www.bmw.be/be/fr/newvehicles/..._datasheet.pdf

[JCL]

Originally Posted by Bayerische E53

Just found the E53 option code. JCL was correct. The option code increases tow capacity to 3500kg (7,700lbs) with a 12% gradient maximum. Actually, the standard towing capacity is also rated at a 12% gradient maximum. The increased towing capacity option was available for the V8 and I6 Diesel cars so I think it's now safe to say that concern here is power rather than chassis strength. As far as the chassis and suspension goes, it looks like the E53 is actually good for 7,700lbs per the manufacturer.

JCL, any input?

See below:

http://www.bmw.be/be/fr/newvehicles/..._datasheet.pdf

I sold my E53 six years ago. Beyond that, I don't know why I remembered 7700/7900 lbs optional tow capacity that was only valid on another continent, but there you go.

Other input?

Good dig out on the old Euro spec sheet.

At least we are now dealing with the E53. I wouldn't keep referring to the E70, it is irrelevant. We need to know what the E53 Euro option code included. Because it was a zero cost option, I suspect it wasn't much. I can't recall the code number, but I suspect it wasn't 233 as the E70 is.

The E53 code specifically requires 18" and larger tires. So it looks like tire loading, and possibly dynamic stability, are issues.

The E53 code specifically excludes the manual transmission 3.0, which doesn't make sense if it just a chassis limitation. I suspect the driveline is not up to it, in BMW's opinion. BMW lets most of their Euro vehicles tow 3500 lbs, with far less HP than the X5 3.0 has. Even my 114 hp Volvo wagon towed 1600 kg/3500 lbs.

While the manufacturer has made reference to 7700 lbs, with specific options that you don't have, they have never permitted that load in North America. So, it may be a combination of mechanical changes and/or legal liability issues. The US hitch is also different, so that could be part of it.

I looked at your pictures of the trailer in another thread. That is a lot of trailer behind a 3.0, in my opinion. You will need to make sure your trailer brakes are working well. And all this speculation about ratings is not as important as driving habits when towing fully loaded, stopping for brake checks when descending mountain passes, etc.

Jeff

[Bayerische E53]

Originally Posted by JCL

I sold my E53 six years ago. Beyond that, I don't know why I remembered 7700/7900 lbs optional tow capacity that was only valid on another continent, but there you go.

Other input?

Good dig out on the old Euro spec sheet.

At least we are now dealing with the E53. I wouldn't keep referring to the E70, it is irrelevant. We need to know what the E53 Euro option code included. Because it was a zero cost option, I suspect it wasn't much. I can't recall the code number, but I suspect it wasn't 233 as the E70 is.

The E53 code specifically requires 18" and larger tires. So it looks like tire loading, and possibly dynamic stability, are issues.

The E53 code specifically excludes the manual transmission 3.0, which doesn't make sense if it just a chassis limitation. I suspect the driveline is not up to it, in BMW's opinion. BMW lets most of their Euro vehicles tow 3500 lbs, with far less HP than the X5 3.0 has. Even my 114 hp Volvo wagon towed 1600 kg/3500 lbs.

While the manufacturer has made reference to 7700 lbs, with specific options that you don't have, they have never permitted that load in North America. So, it may be a combination of mechanical changes and/or legal liability issues. The US hitch is also different, so that could be part of it.

I looked at your pictures of the trailer in another thread. That is a lot of trailer behind a 3.0, in my opinion. You will need to make sure your trailer brakes are working well. And all this speculation about ratings is not as important as driving habits when towing fully loaded, stopping for brake checks when descending mountain passes, etc.

Jeff

Some Points:

1. The Wheels. I saw the bit about 18" wheels. I will have 4.8is wheels on the car and will outfit them with the highest load rated tire I can find so no problem there.

2. The Driveline. The E53 code excludes both the manual and automatic 3L but not the 3Ld, which makes me believe it is a power thing. But, I see what you mean about BMW allowing smaller and lower powered cars tow 3,500lbs. That said, it might be a clutch thing on the manual. It might just be a transmission thing. I'll have to check into it more. I'm actually going to check whether the diesel transmission is the same as the one on the petrol engine. If it is, then it's got to be a torque/power thing. Otherwise, I'll just be more confused and have more questions. As I said, I'll be on the phone with BMW tomorrow to check on this and on the other options that come with this option code. I know that one such option is Trailer Stability Control; an option which is presumably an on/off type thing that can be accomplished with a GT1 as it functions through the ABS/ASC/DSC or whatever. Again, however, I'll have to confirm with BMW.

3. The Hitch. Yes, the Euro hitches are different. I'm going to ask BMW about this and will also touch base with Westfalia about it. Many say Westfalia's actual rating is higher but that they label it at 6,000lbs because that's what BMW says. I'll have to confirm with them as it's currently hearsay.

4. Mechanical Changes/Legal Issues. I'll also talk to BMW as to why this option was not offered on the U.S. cars. Could have been a marketing thing - could have been a more legitimate reason. I'll have to confirm.

5. The trailer. Yes, the trailer is a sizable piece of equipment. However, it is shorter in length and height (well, and weight, obviously) than Withidl's Airstream. I understand that the Airstream is more rounded, but at 6-12" taller, I'd say the aero drag is approximate (albeit probably a bit, but not much, more on my trailer).

6. The Driver. You're absolutely correct about the driver. It is driver habits, preparation, and monitoring that will carry the day. Of course, those won't make up for towing an unspeakably stupid load on an X5 (e.g. 12,000lbs). However, assuming everything checks out with BMW about the Euro tow capacity option, I should think that 7,500lbs would be a load that a diligent driver can handle as the chassis (again, assuming the equipment is up to Euro spec.) can handle it. This is going to be the deciding factor.

7. The Actual Drive. As you probably saw in the other thread, I won't be towing the trailer fully loaded at the first instance. I'm going to see how she tows unloaded, then loaded with the car, then fully loaded. Actually, I'll probably go unloaded, then loaded with full kit without the car, then fully loaded with the car. If the X5 can't do any one of those due to the drag, it's Cummins or 1/2 ton time. If the latter, I've got an open deck I can still putz around with in the mean time.